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+Table of Contents
+*****************
+
+GNU GRUB manual
+1 Introduction to GRUB
+ 1.1 Overview
+ 1.2 History of GRUB
+ 1.3 GRUB features
+ 1.4 The role of a boot loader
+2 Naming convention
+3 Installation
+ 3.1 Creating a GRUB boot floppy
+ 3.2 Installing GRUB natively
+ 3.3 Installing GRUB using grub-install
+ 3.4 Making a GRUB bootable CD-ROM
+4 Booting
+ 4.1 How to boot operating systems
+ 4.1.1 How to boot an OS directly with GRUB
+ 4.1.2 Load another boot loader to boot unsupported operating systems
+ 4.2 Some caveats on OS-specific issues
+ 4.2.1 GNU/Hurd
+ 4.2.2 GNU/Linux
+ 4.2.3 FreeBSD
+ 4.2.4 NetBSD
+ 4.2.5 OpenBSD
+ 4.2.6 DOS/Windows
+ 4.2.7 SCO UnixWare
+ 4.2.8 QNX
+ 4.3 How to make your system robust
+ 4.3.1 Booting once-only
+ 4.3.2 Booting fallback systems
+5 Configuration
+6 Downloading OS images from a network
+ 6.1 How to set up your network
+ 6.2 Booting from a network
+7 Using GRUB via a serial line
+8 Embedding a configuration file into GRUB
+9 Protecting your computer from cracking
+10 GRUB image files
+11 Filesystem syntax and semantics
+ 11.1 How to specify devices
+ 11.2 How to specify files
+ 11.3 How to specify block lists
+12 GRUB's user interface
+ 12.1 The flexible command-line interface
+ 12.2 The simple menu interface
+ 12.3 Editing a menu entry
+ 12.4 The hidden menu interface
+13 The list of available commands
+ 13.1 The list of commands for the menu only
+ 13.1.1 default
+ 13.1.2 fallback
+ 13.1.3 hiddenmenu
+ 13.1.4 timeout
+ 13.1.5 title
+ 13.2 The list of general commands
+ 13.2.1 bootp
+ 13.2.2 color
+ 13.2.3 device
+ 13.2.4 dhcp
+ 13.2.5 hide
+ 13.2.6 ifconfig
+ 13.2.7 pager
+ 13.2.8 partnew
+ 13.2.9 parttype
+ 13.2.10 password
+ 13.2.11 rarp
+ 13.2.12 serial
+ 13.2.13 setkey
+ 13.2.14 terminal
+ 13.2.15 terminfo
+ 13.2.16 tftpserver
+ 13.2.17 unhide
+ 13.3 The list of command-line and menu entry commands
+ 13.3.1 blocklist
+ 13.3.2 boot
+ 13.3.3 cat
+ 13.3.4 chainloader
+ 13.3.5 cmp
+ 13.3.6 configfile
+ 13.3.7 debug
+ 13.3.8 displayapm
+ 13.3.9 displaymem
+ 13.3.10 embed
+ 13.3.11 find
+ 13.3.12 fstest
+ 13.3.13 geometry
+ 13.3.14 halt
+ 13.3.15 help
+ 13.3.16 impsprobe
+ 13.3.17 initrd
+ 13.3.18 install
+ 13.3.19 ioprobe
+ 13.3.20 kernel
+ 13.3.21 lock
+ 13.3.22 makeactive
+ 13.3.23 map
+ 13.3.24 md5crypt
+ 13.3.25 module
+ 13.3.26 modulenounzip
+ 13.3.27 pause
+ 13.3.28 quit
+ 13.3.29 reboot
+ 13.3.30 read
+ 13.3.31 root
+ 13.3.32 rootnoverify
+ 13.3.33 savedefault
+ 13.3.34 setup
+ 13.3.35 testload
+ 13.3.36 testvbe
+ 13.3.37 uppermem
+ 13.3.38 vbeprobe
+14 Error messages reported by GRUB
+ 14.1 Errors reported by the Stage 1
+ 14.2 Errors reported by the Stage 1.5
+ 14.3 Errors reported by the Stage 2
+15 Invoking the grub shell
+ 15.1 Introduction into the grub shell
+ 15.2 How to install GRUB via `grub'
+ 15.3 The map between BIOS drives and OS devices
+16 Invoking grub-install
+17 Invoking grub-md5-crypt
+18 Invoking grub-terminfo
+19 Invoking grub-set-default
+20 Invoking mbchk
+Appendix A How to obtain and build GRUB
+Appendix B Reporting bugs
+Appendix C Where GRUB will go
+Appendix D Hacking GRUB
+ D.1 The memory map of various components
+ D.2 Embedded variables in GRUB
+ D.3 The generic interface for filesystems
+ D.4 The generic interface for built-ins
+ D.5 The bootstrap mechanism used in GRUB
+ D.6 How to probe I/O ports used by INT 13H
+ D.7 How to detect all installed RAM
+ D.8 INT 13H disk I/O interrupts
+ D.9 The structure of Master Boot Record
+ D.10 The format of partition tables
+ D.11 Where and how you should send patches
+Appendix E Copying This Manual
+ E.1 GNU Free Documentation License
+ E.1.1 ADDENDUM: How to use this License for your documents
+Index
+
+
+GNU GRUB manual
+***************
+
+This is the documentation of GNU GRUB, the GRand Unified Bootloader, a
+flexible and powerful boot loader program for PCs.
+
+ This edition documents version 0.97.
+
+ This manual is for GNU GRUB (version 0.97, 8 May 2005).
+
+ Copyright (C) 1999,2000,2001,2002,2004,2006 Free Software
+Foundation, Inc.
+
+ Permission is granted to copy, distribute and/or modify this
+ document under the terms of the GNU Free Documentation License,
+ Version 1.2 or any later version published by the Free Software
+ Foundation; with no Invariant Sections, with the Front-Cover Texts
+ being "A GNU Manual," and with the Back-Cover Texts as in (a)
+ below. A copy of the license is included in the section entitled
+ "GNU Free Documentation License."
+
+ (a) The FSF's Back-Cover Text is: "You have freedom to copy and
+ modify this GNU Manual, like GNU software. Copies published by
+ the Free Software Foundation raise funds for GNU development."
+
+1 Introduction to GRUB
+**********************
+
+1.1 Overview
+============
+
+Briefly, a "boot loader" is the first software program that runs when a
+computer starts. It is responsible for loading and transferring
+control to an operating system "kernel" software (such as Linux or GNU
+Mach). The kernel, in turn, initializes the rest of the operating
+system (e.g. a GNU system).
+
+ GNU GRUB is a very powerful boot loader, which can load a wide
+variety of free operating systems, as well as proprietary operating
+systems with chain-loading(1) (*note Overview-Footnote-1::). GRUB is
+designed to address the complexity of booting a personal computer; both
+the program and this manual are tightly bound to that computer platform,
+although porting to other platforms may be addressed in the future.
+
+ One of the important features in GRUB is flexibility; GRUB
+understands filesystems and kernel executable formats, so you can load
+an arbitrary operating system the way you like, without recording the
+physical position of your kernel on the disk. Thus you can load the
+kernel just by specifying its file name and the drive and partition
+where the kernel resides.
+
+ When booting with GRUB, you can use either a command-line interface
+(*note Command-line interface::), or a menu interface (*note Menu
+interface::). Using the command-line interface, you type the drive
+specification and file name of the kernel manually. In the menu
+interface, you just select an OS using the arrow keys. The menu is
+based on a configuration file which you prepare beforehand (*note
+Configuration::). While in the menu, you can switch to the command-line
+mode, and vice-versa. You can even edit menu entries before using them.
+
+ In the following chapters, you will learn how to specify a drive, a
+partition, and a file name (*note Naming convention::) to GRUB, how to
+install GRUB on your drive (*note Installation::), and how to boot your
+OSes (*note Booting::), step by step.
+
+ Besides the GRUB boot loader itself, there is a "grub shell" `grub'
+(*note Invoking the grub shell::) which can be run when you are in your
+operating system. It emulates the boot loader and can be used for
+installing the boot loader.
+
+ (1) "chain-load" is the mechanism for loading unsupported operating
+systems by loading another boot loader. It is typically used for
+loading DOS or Windows.
+
+1.2 History of GRUB
+===================
+
+GRUB originated in 1995 when Erich Boleyn was trying to boot the GNU
+Hurd with the University of Utah's Mach 4 microkernel (now known as GNU
+Mach). Erich and Brian Ford designed the Multiboot Specification
+(*note Multiboot Specification: (multiboot)Top.), because they were
+determined not to add to the large number of mutually-incompatible PC
+boot methods.
+
+ Erich then began modifying the FreeBSD boot loader so that it would
+understand Multiboot. He soon realized that it would be a lot easier to
+write his own boot loader from scratch than to keep working on the
+FreeBSD boot loader, and so GRUB was born.
+
+ Erich added many features to GRUB, but other priorities prevented him
+from keeping up with the demands of its quickly-expanding user base. In
+1999, Gordon Matzigkeit and Yoshinori K. Okuji adopted GRUB as an
+official GNU package, and opened its development by making the latest
+sources available via anonymous CVS. *Note Obtaining and Building
+GRUB::, for more information.
+
+1.3 GRUB features
+=================
+
+The primary requirement for GRUB is that it be compliant with the
+"Multiboot Specification", which is described in *Note Multiboot
+Specification: (multiboot)Top.
+
+ The other goals, listed in approximate order of importance, are:
+
+ * Basic functions must be straightforward for end-users.
+
+ * Rich functionality to support kernel experts and designers.
+
+ * Backward compatibility for booting FreeBSD, NetBSD, OpenBSD, and
+ Linux. Proprietary kernels (such as DOS, Windows NT, and OS/2) are
+ supported via a chain-loading function.
+
+ Except for specific compatibility modes (chain-loading and the Linux
+"piggyback" format), all kernels will be started in much the same state
+as in the Multiboot Specification. Only kernels loaded at 1 megabyte or
+above are presently supported. Any attempt to load below that boundary
+will simply result in immediate failure and an error message reporting
+the problem.
+
+ In addition to the requirements above, GRUB has the following
+features (note that the Multiboot Specification doesn't require all the
+features that GRUB supports):
+
+Recognize multiple executable formats
+ Support many of the "a.out" variants plus "ELF". Symbol tables are
+ also loaded.
+
+Support non-Multiboot kernels
+ Support many of the various free 32-bit kernels that lack Multiboot
+ compliance (primarily FreeBSD, NetBSD, OpenBSD, and Linux).
+ Chain-loading of other boot loaders is also supported.
+
+Load multiples modules
+ Fully support the Multiboot feature of loading multiple modules.
+
+Load a configuration file
+ Support a human-readable text configuration file with preset boot
+ commands. You can also load another configuration file dynamically
+ and embed a preset configuration file in a GRUB image file. The
+ list of commands (*note Commands::) are a superset of those
+ supported on the command-line. An example configuration file is
+ provided in *Note Configuration::.
+
+Provide a menu interface
+ A menu interface listing preset boot commands, with a programmable
+ timeout, is available. There is no fixed limit on the number of
+ boot entries, and the current implementation has space for several
+ hundred.
+
+Have a flexible command-line interface
+ A fairly flexible command-line interface, accessible from the menu,
+ is available to edit any preset commands, or write a new boot
+ command set from scratch. If no configuration file is present,
+ GRUB drops to the command-line.
+
+ The list of commands (*note Commands::) are a subset of those
+ supported for configuration files. Editing commands closely
+ resembles the Bash command-line (*note Bash: (features)Command
+ Line Editing.), with <TAB>-completion of commands, devices,
+ partitions, and files in a directory depending on context.
+
+Support multiple filesystem types
+ Support multiple filesystem types transparently, plus a useful
+ explicit blocklist notation. The currently supported filesystem
+ types are "BSD FFS", "DOS FAT16 and FAT32", "Minix fs", "Linux
+ ext2fs", "ReiserFS", "JFS", "XFS", and "VSTa fs". *Note
+ Filesystem::, for more information.
+
+Support automatic decompression
+ Can decompress files which were compressed by `gzip'. This
+ function is both automatic and transparent to the user (i.e. all
+ functions operate upon the uncompressed contents of the specified
+ files). This greatly reduces a file size and loading time, a
+ particularly great benefit for floppies.(1) (*note
+ Features-Footnote-1::)
+
+ It is conceivable that some kernel modules should be loaded in a
+ compressed state, so a different module-loading command can be
+ specified to avoid uncompressing the modules.
+
+Access data on any installed device
+ Support reading data from any or all floppies or hard disk(s)
+ recognized by the BIOS, independent of the setting of the root
+ device.
+
+Be independent of drive geometry translations
+ Unlike many other boot loaders, GRUB makes the particular drive
+ translation irrelevant. A drive installed and running with one
+ translation may be converted to another translation without any
+ adverse effects or changes in GRUB's configuration.
+
+Detect all installed RAM
+ GRUB can generally find all the installed RAM on a PC-compatible
+ machine. It uses an advanced BIOS query technique for finding all
+ memory regions. As described on the Multiboot Specification (*note
+ Multiboot Specification: (multiboot)Top.), not all kernels make
+ use of this information, but GRUB provides it for those who do.
+
+Support Logical Block Address mode
+ In traditional disk calls (called "CHS mode"), there is a geometry
+ translation problem, that is, the BIOS cannot access over 1024
+ cylinders, so the accessible space is limited to at least 508 MB
+ and to at most 8GB. GRUB can't universally solve this problem, as
+ there is no standard interface used in all machines. However,
+ several newer machines have the new interface, Logical Block
+ Address ("LBA") mode. GRUB automatically detects if LBA mode is
+ available and uses it if available. In LBA mode, GRUB can access
+ the entire disk.
+
+Support network booting
+ GRUB is basically a disk-based boot loader but also has network
+ support. You can load OS images from a network by using the "TFTP"
+ protocol.
+
+Support remote terminals
+ To support computers with no console, GRUB provides remote terminal
+ support, so that you can control GRUB from a remote host. Only
+ serial terminal support is implemented at the moment.
+
+ (1) There are a few pathological cases where loading a very badly
+organized ELF kernel might take longer, but in practice this never
+happen.
+
+1.4 The role of a boot loader
+=============================
+
+The following is a quotation from Gordon Matzigkeit, a GRUB fanatic:
+
+ Some people like to acknowledge both the operating system and
+ kernel when they talk about their computers, so they might say
+ they use "GNU/Linux" or "GNU/Hurd". Other people seem to think
+ that the kernel is the most important part of the system, so they
+ like to call their GNU operating systems "Linux systems."
+
+ I, personally, believe that this is a grave injustice, because the
+ _boot loader_ is the most important software of all. I used to
+ refer to the above systems as either "LILO"(1) (*note Role of a
+ boot loader-Footnote-1::) or "GRUB" systems.
+
+ Unfortunately, nobody ever understood what I was talking about;
+ now I just use the word "GNU" as a pseudonym for GRUB.
+
+ So, if you ever hear people talking about their alleged "GNU"
+ systems, remember that they are actually paying homage to the best
+ boot loader around... GRUB!
+
+ We, the GRUB maintainers, do not (usually) encourage Gordon's level
+of fanaticism, but it helps to remember that boot loaders deserve
+recognition. We hope that you enjoy using GNU GRUB as much as we did
+writing it.
+
+ (1) The LInux LOader, a boot loader that everybody uses, but nobody
+likes.
+
+2 Naming convention
+*******************
+
+The device syntax used in GRUB is a wee bit different from what you may
+have seen before in your operating system(s), and you need to know it so
+that you can specify a drive/partition.
+
+ Look at the following examples and explanations:
+
+ (fd0)
+
+ First of all, GRUB requires that the device name be enclosed with
+`(' and `)'. The `fd' part means that it is a floppy disk. The number
+`0' is the drive number, which is counted from _zero_. This expression
+means that GRUB will use the whole floppy disk.
+
+ (hd0,1)
+
+ Here, `hd' means it is a hard disk drive. The first integer `0'
+indicates the drive number, that is, the first hard disk, while the
+second integer, `1', indicates the partition number (or the PC slice
+number in the BSD terminology). Once again, please note that the
+partition numbers are counted from _zero_, not from one. This
+expression means the second partition of the first hard disk drive. In
+this case, GRUB uses one partition of the disk, instead of the whole
+disk.
+
+ (hd0,4)
+
+ This specifies the first "extended partition" of the first hard disk
+drive. Note that the partition numbers for extended partitions are
+counted from `4', regardless of the actual number of primary partitions
+on your hard disk.
+
+ (hd1,a)
+
+ This means the BSD `a' partition of the second hard disk. If you
+need to specify which PC slice number should be used, use something
+like this: `(hd1,0,a)'. If the PC slice number is omitted, GRUB
+searches for the first PC slice which has a BSD `a' partition.
+
+ Of course, to actually access the disks or partitions with GRUB, you
+need to use the device specification in a command, like `root (fd0)' or
+`unhide (hd0,2)'. To help you find out which number specifies a
+partition you want, the GRUB command-line (*note Command-line
+interface::) options have argument completion. This means that, for
+example, you only need to type
+
+ root (
+
+ followed by a <TAB>, and GRUB will display the list of drives,
+partitions, or file names. So it should be quite easy to determine the
+name of your target partition, even with minimal knowledge of the
+syntax.
+
+ Note that GRUB does _not_ distinguish IDE from SCSI - it simply
+counts the drive numbers from zero, regardless of their type. Normally,
+any IDE drive number is less than any SCSI drive number, although that
+is not true if you change the boot sequence by swapping IDE and SCSI
+drives in your BIOS.
+
+ Now the question is, how to specify a file? Again, consider an
+example:
+
+ (hd0,0)/vmlinuz
+
+ This specifies the file named `vmlinuz', found on the first
+partition of the first hard disk drive. Note that the argument
+completion works with file names, too.
+
+ That was easy, admit it. Now read the next chapter, to find out how
+to actually install GRUB on your drive.
+
+3 Installation
+**************
+
+In order to install GRUB as your boot loader, you need to first install
+the GRUB system and utilities under your UNIX-like operating system
+(*note Obtaining and Building GRUB::). You can do this either from the
+source tarball, or as a package for your OS.
+
+ After you have done that, you need to install the boot loader on a
+drive (floppy or hard disk). There are two ways of doing that - either
+using the utility `grub-install' (*note Invoking grub-install::) on a
+UNIX-like OS, or by running GRUB itself from a floppy. These are quite
+similar, however the utility might probe a wrong BIOS drive, so you
+should be careful.
+
+ Also, if you install GRUB on a UNIX-like OS, please make sure that
+you have an emergency boot disk ready, so that you can rescue your
+computer if, by any chance, your hard drive becomes unusable
+(unbootable).
+
+ GRUB comes with boot images, which are normally put in the directory
+`/usr/lib/grub/i386-pc'. If you do not use grub-install, then you need
+to copy the files `stage1', `stage2', and `*stage1_5' to the directory
+`/boot/grub', and run the `grub-set-default' (*note Invoking
+grub-set-default::) if you intend to use `default saved' (*note
+default::) in your configuration file. Hereafter, the directory where
+GRUB images are initially placed (normally `/usr/lib/grub/i386-pc')
+will be called the "image directory", and the directory where the boot
+loader needs to find them (usually `/boot/grub') will be called the
+"boot directory".
+
+3.1 Creating a GRUB boot floppy
+===============================
+
+To create a GRUB boot floppy, you need to take the files `stage1' and
+`stage2' from the image directory, and write them to the first and the
+second block of the floppy disk, respectively.
+
+ *Caution:* This procedure will destroy any data currently stored on
+the floppy.
+
+ On a UNIX-like operating system, that is done with the following
+commands:
+
+ # cd /usr/lib/grub/i386-pc
+ # dd if=stage1 of=/dev/fd0 bs=512 count=1
+ 1+0 records in
+ 1+0 records out
+ # dd if=stage2 of=/dev/fd0 bs=512 seek=1
+ 153+1 records in
+ 153+1 records out
+ #
+
+ The device file name may be different. Consult the manual for your
+OS.
+
+3.2 Installing GRUB natively
+============================
+
+*Caution:* Installing GRUB's stage1 in this manner will erase the
+normal boot-sector used by an OS.
+
+ GRUB can currently boot GNU Mach, Linux, FreeBSD, NetBSD, and OpenBSD
+directly, so using it on a boot sector (the first sector of a
+partition) should be okay. But generally, it would be a good idea to
+back up the first sector of the partition on which you are installing
+GRUB's stage1. This isn't as important if you are installing GRUB on
+the first sector of a hard disk, since it's easy to reinitialize it
+(e.g. by running `FDISK /MBR' from DOS).
+
+ If you decide to install GRUB in the native environment, which is
+definitely desirable, you'll need to create a GRUB boot disk, and
+reboot your computer with it. Otherwise, see *Note Installing GRUB
+using grub-install::.
+
+ Once started, GRUB will show the command-line interface (*note
+Command-line interface::). First, set the GRUB's "root device"(1)
+(*note Installing GRUB natively-Footnote-1::) to the partition
+containing the boot directory, like this:
+
+ grub> root (hd0,0)
+
+ If you are not sure which partition actually holds this directory,
+use the command `find' (*note find::), like this:
+
+ grub> find /boot/grub/stage1
+
+ This will search for the file name `/boot/grub/stage1' and show the
+devices which contain the file.
+
+ Once you've set the root device correctly, run the command `setup'
+(*note setup::):
+
+ grub> setup (hd0)
+
+ This command will install the GRUB boot loader on the Master Boot
+Record (MBR) of the first drive. If you want to put GRUB into the boot
+sector of a partition instead of putting it in the MBR, specify the
+partition into which you want to install GRUB:
+
+ grub> setup (hd0,0)
+
+ If you install GRUB into a partition or a drive other than the first
+one, you must chain-load GRUB from another boot loader. Refer to the
+manual for the boot loader to know how to chain-load GRUB.
+
+ After using the setup command, you will boot into GRUB without the
+GRUB floppy. See the chapter *Note Booting:: to find out how to boot
+your operating systems from GRUB.
+
+ (1) Note that GRUB's root device doesn't necessarily mean your OS's
+root partition; if you need to specify a root partition for your OS,
+add the argument into the command `kernel'.
+
+3.3 Installing GRUB using grub-install
+======================================
+
+*Caution:* This procedure is definitely less safe, because there are
+several ways in which your computer can become unbootable. For example,
+most operating systems don't tell GRUB how to map BIOS drives to OS
+devices correctly--GRUB merely "guesses" the mapping. This will succeed
+in most cases, but not always. Therefore, GRUB provides you with a map
+file called the "device map", which you must fix if it is wrong. *Note
+Device map::, for more details.
+
+ If you still do want to install GRUB under a UNIX-like OS (such as
+GNU), invoke the program `grub-install' (*note Invoking grub-install::)
+as the superuser ("root").
+
+ The usage is basically very simple. You only need to specify one
+argument to the program, namely, where to install the boot loader. The
+argument can be either a device file (like `/dev/hda') or a partition
+specified in GRUB's notation. For example, under Linux the following
+will install GRUB into the MBR of the first IDE disk:
+
+ # grub-install /dev/hda
+
+ Likewise, under GNU/Hurd, this has the same effect:
+
+ # grub-install /dev/hd0
+
+ If it is the first BIOS drive, this is the same as well:
+
+ # grub-install '(hd0)'
+
+ Or you can omit the parentheses:
+
+ # grub-install hd0
+
+ But all the above examples assume that GRUB should use images under
+the root directory. If you want GRUB to use images under a directory
+other than the root directory, you need to specify the option
+`--root-directory'. The typical usage is that you create a GRUB boot
+floppy with a filesystem. Here is an example:
+
+ # mke2fs /dev/fd0
+ # mount -t ext2 /dev/fd0 /mnt
+ # grub-install --root-directory=/mnt fd0
+ # umount /mnt
+
+ Another example is when you have a separate boot partition which is
+mounted at `/boot'. Since GRUB is a boot loader, it doesn't know
+anything about mountpoints at all. Thus, you need to run `grub-install'
+like this:
+
+ # grub-install --root-directory=/boot /dev/hda
+
+ By the way, as noted above, it is quite difficult to guess BIOS
+drives correctly under a UNIX-like OS. Thus, `grub-install' will prompt
+you to check if it could really guess the correct mappings, after the
+installation. The format is defined in *Note Device map::. Please be
+quite careful. If the output is wrong, it is unlikely that your
+computer will be able to boot with no problem.
+
+ Note that `grub-install' is actually just a shell script and the
+real task is done by the grub shell `grub' (*note Invoking the grub
+shell::). Therefore, you may run `grub' directly to install GRUB,
+without using `grub-install'. Don't do that, however, unless you are
+very familiar with the internals of GRUB. Installing a boot loader on a
+running OS may be extremely dangerous.
+
+3.4 Making a GRUB bootable CD-ROM
+=================================
+
+GRUB supports the "no emulation mode" in the El Torito specification(1)
+(*note Making a GRUB bootable CD-ROM-Footnote-1::). This means that you
+can use the whole CD-ROM from GRUB and you don't have to make a floppy
+or hard disk image file, which can cause compatibility problems.
+
+ For booting from a CD-ROM, GRUB uses a special Stage 2 called
+`stage2_eltorito'. The only GRUB files you need to have in your
+bootable CD-ROM are this `stage2_eltorito' and optionally a config file
+`menu.lst'. You don't need to use `stage1' or `stage2', because El
+Torito is quite different from the standard boot process.
+
+ Here is an example of procedures to make a bootable CD-ROM image.
+First, make a top directory for the bootable image, say, `iso':
+
+ $ mkdir iso
+
+ Make a directory for GRUB:
+
+ $ mkdir -p iso/boot/grub
+
+ Copy the file `stage2_eltorito':
+
+ $ cp /usr/lib/grub/i386-pc/stage2_eltorito iso/boot/grub
+
+ If desired, make the config file `menu.lst' under `iso/boot/grub'
+(*note Configuration::), and copy any files and directories for the
+disc to the directory `iso/'.
+
+ Finally, make a ISO9660 image file like this:
+
+ $ mkisofs -R -b boot/grub/stage2_eltorito -no-emul-boot \
+ -boot-load-size 4 -boot-info-table -o grub.iso iso
+
+ This produces a file named `grub.iso', which then can be burned into
+a CD (or a DVD). `mkisofs' has already set up the disc to boot from
+the `boot/grub/stage2_eltorito' file, so there is no need to setup GRUB
+on the disc. (Note that the `-boot-load-size 4' bit is required for
+compatibility with the BIOS on many older machines.)
+
+ You can use the device `(cd)' to access a CD-ROM in your config
+file. This is not required; GRUB automatically sets the root device to
+`(cd)' when booted from a CD-ROM. It is only necessary to refer to
+`(cd)' if you want to access other drives as well.
+
+ (1) El Torito is a specification for bootable CD using BIOS
+functions.
+
+4 Booting
+*********
+
+GRUB can load Multiboot-compliant kernels in a consistent way, but for
+some free operating systems you need to use some OS-specific magic.
+
+4.1 How to boot operating systems
+=================================
+
+GRUB has two distinct boot methods. One of the two is to load an
+operating system directly, and the other is to chain-load another boot
+loader which then will load an operating system actually. Generally
+speaking, the former is more desirable, because you don't need to
+install or maintain other boot loaders and GRUB is flexible enough to
+load an operating system from an arbitrary disk/partition. However, the
+latter is sometimes required, since GRUB doesn't support all the
+existing operating systems natively.
+
+4.1.1 How to boot an OS directly with GRUB
+------------------------------------------
+
+Multiboot (*note Multiboot Specification: (multiboot)Top.) is the
+native format supported by GRUB. For the sake of convenience, there is
+also support for Linux, FreeBSD, NetBSD and OpenBSD. If you want to
+boot other operating systems, you will have to chain-load them (*note
+Chain-loading::).
+
+ Generally, GRUB can boot any Multiboot-compliant OS in the following
+steps:
+
+ 1. Set GRUB's root device to the drive where the OS images are stored
+ with the command `root' (*note root::).
+
+ 2. Load the kernel image with the command `kernel' (*note kernel::).
+
+ 3. If you need modules, load them with the command `module' (*note
+ module::) or `modulenounzip' (*note modulenounzip::).
+
+ 4. Run the command `boot' (*note boot::).
+
+ Linux, FreeBSD, NetBSD and OpenBSD can be booted in a similar
+manner. You load a kernel image with the command `kernel' and then run
+the command `boot'. If the kernel requires some parameters, just append
+the parameters to `kernel', after the file name of the kernel. Also,
+please refer to *Note OS-specific notes::, for information on your
+OS-specific issues.
+
+4.1.2 Load another boot loader to boot unsupported operating systems
+--------------------------------------------------------------------
+
+If you want to boot an unsupported operating system (e.g. Windows 95),
+chain-load a boot loader for the operating system. Normally, the boot
+loader is embedded in the "boot sector" of the partition on which the
+operating system is installed.
+
+ 1. Set GRUB's root device to the partition by the command
+ `rootnoverify' (*note rootnoverify::):
+
+ grub> rootnoverify (hd0,0)
+
+ 2. Set the "active" flag in the partition using the command
+ `makeactive'(1) (*note Chain-loading-Footnote-1::) (*note
+ makeactive::):
+
+ grub> makeactive
+
+ 3. Load the boot loader with the command `chainloader' (*note
+ chainloader::):
+
+ grub> chainloader +1
+
+ `+1' indicates that GRUB should read one sector from the start of
+ the partition. The complete description about this syntax can be
+ found in *Note Block list syntax::.
+
+ 4. Run the command `boot' (*note boot::).
+
+ However, DOS and Windows have some deficiencies, so you might have to
+use more complicated instructions. *Note DOS/Windows::, for more
+information.
+
+ (1) This is not necessary for most of the modern operating systems.
+
+4.2 Some caveats on OS-specific issues
+======================================
+
+Here, we describe some caveats on several operating systems.
+
+4.2.1 GNU/Hurd
+--------------
+
+Since GNU/Hurd is Multiboot-compliant, it is easy to boot it; there is
+nothing special about it. But do not forget that you have to specify a
+root partition to the kernel.
+
+ 1. Set GRUB's root device to the same drive as GNU/Hurd's. Probably
+ the command `find /boot/gnumach' or similar can help you (*note
+ find::).
+
+ 2. Load the kernel and the module, like this:
+
+ grub> kernel /boot/gnumach root=hd0s1
+ grub> module /boot/serverboot
+
+ 3. Run the command `boot' (*note boot::).
+
+4.2.2 GNU/Linux
+---------------
+
+It is relatively easy to boot GNU/Linux from GRUB, because it somewhat
+resembles to boot a Multiboot-compliant OS.
+
+ 1. Set GRUB's root device to the same drive as GNU/Linux's. Probably
+ the command `find /vmlinuz' or similar can help you (*note find::).
+
+ 2. Load the kernel:
+
+ grub> kernel /vmlinuz root=/dev/hda1
+
+ If you need to specify some kernel parameters, just append them to
+ the command. For example, to set `vga' to `ext', do this:
+
+ grub> kernel /vmlinuz root=/dev/hda1 vga=ext
+
+ See the documentation in the Linux source tree for complete
+ information on the available options.
+
+ 3. If you use an initrd, execute the command `initrd' (*note
+ initrd::) after `kernel':
+
+ grub> initrd /initrd
+
+ 4. Finally, run the command `boot' (*note boot::).
+
+ *Caution:* If you use an initrd and specify the `mem=' option to the
+kernel to let it use less than actual memory size, you will also have
+to specify the same memory size to GRUB. To let GRUB know the size, run
+the command `uppermem' _before_ loading the kernel. *Note uppermem::,
+for more information.
+
+4.2.3 FreeBSD
+-------------
+
+GRUB can load the kernel directly, either in ELF or a.out format. But
+this is not recommended, since FreeBSD's bootstrap interface sometimes
+changes heavily, so GRUB can't guarantee to pass kernel parameters
+correctly.
+
+ Thus, we'd recommend loading the very flexible loader `/boot/loader'
+instead. See this example:
+
+ grub> root (hd0,a)
+ grub> kernel /boot/loader
+ grub> boot
+
+4.2.4 NetBSD
+------------
+
+GRUB can load NetBSD a.out and ELF directly, follow these steps:
+
+ 1. Set GRUB's root device with `root' (*note root::).
+
+ 2. Load the kernel with `kernel' (*note kernel::). You should append
+ the ugly option `--type=netbsd', if you want to load an ELF
+ kernel, like this:
+
+ grub> kernel --type=netbsd /netbsd-elf
+
+ 3. Run `boot' (*note boot::).
+
+ For now, however, GRUB doesn't allow you to pass kernel parameters,
+so it may be better to chain-load it instead. For more information,
+please see *Note Chain-loading::.
+
+4.2.5 OpenBSD
+-------------
+
+The booting instruction is exactly the same as for NetBSD (*note
+NetBSD::).
+
+4.2.6 DOS/Windows
+-----------------
+
+GRUB cannot boot DOS or Windows directly, so you must chain-load them
+(*note Chain-loading::). However, their boot loaders have some critical
+deficiencies, so it may not work to just chain-load them. To overcome
+the problems, GRUB provides you with two helper functions.
+
+ If you have installed DOS (or Windows) on a non-first hard disk, you
+have to use the disk swapping technique, because that OS cannot boot
+from any disks but the first one. The workaround used in GRUB is the
+command `map' (*note map::), like this:
+
+ grub> map (hd0) (hd1)
+ grub> map (hd1) (hd0)
+
+ This performs a "virtual" swap between your first and second hard
+drive.
+
+ *Caution:* This is effective only if DOS (or Windows) uses BIOS to
+access the swapped disks. If that OS uses a special driver for the
+disks, this probably won't work.
+
+ Another problem arises if you installed more than one set of
+DOS/Windows onto one disk, because they could be confused if there are
+more than one primary partitions for DOS/Windows. Certainly you should
+avoid doing this, but there is a solution if you do want to do so. Use
+the partition hiding/unhiding technique.
+
+ If GRUB "hide"s a DOS (or Windows) partition (*note hide::), DOS (or
+Windows) will ignore the partition. If GRUB "unhide"s a DOS (or
+Windows) partition (*note unhide::), DOS (or Windows) will detect the
+partition. Thus, if you have installed DOS (or Windows) on the first
+and the second partition of the first hard disk, and you want to boot
+the copy on the first partition, do the following:
+
+ grub> unhide (hd0,0)
+ grub> hide (hd0,1)
+ grub> rootnoverify (hd0,0)
+ grub> chainloader +1
+ grub> makeactive
+ grub> boot
+
+4.2.7 SCO UnixWare
+------------------
+
+It is known that the signature in the boot loader for SCO UnixWare is
+wrong, so you will have to specify the option `--force' to
+`chainloader' (*note chainloader::), like this:
+
+ grub> rootnoverify (hd1,0)
+ grub> chainloader --force +1
+ grub> makeactive
+ grub> boot
+
+4.2.8 QNX
+---------
+
+QNX seems to use a bigger boot loader, so you need to boot it up, like
+this:
+
+ grub> rootnoverify (hd1,1)
+ grub> chainloader +4
+ grub> boot
+
+4.3 How to make your system robust
+==================================
+
+When you test a new kernel or a new OS, it is important to make sure
+that your computer can boot even if the new system is unbootable. This
+is crucial especially if you maintain servers or remote systems. To
+accomplish this goal, you need to set up two things:
+
+ 1. You must maintain a system which is always bootable. For instance,
+ if you test a new kernel, you need to keep a working kernel in a
+ different place. And, it would sometimes be very nice to even have
+ a complete copy of a working system in a different partition or
+ disk.
+
+ 2. You must direct GRUB to boot a working system when the new system
+ fails. This is possible with the "fallback" system in GRUB.
+
+ The former requirement is very specific to each OS, so this
+documentation does not cover that topic. It is better to consult some
+backup tools.
+
+ So let's see the GRUB part. There are two possibilities: one of them
+is quite simple but not very robust, and the other is a bit complex to
+set up but probably the best solution to make sure that your system can
+start as long as GRUB itself is bootable.
+
+4.3.1 Booting once-only
+-----------------------
+
+You can teach GRUB to boot an entry only at next boot time. Suppose
+that your have an old kernel `old_kernel' and a new kernel
+`new_kernel'. You know that `old_kernel' can boot your system
+correctly, and you want to test `new_kernel'.
+
+ To ensure that your system will go back to the old kernel even if the
+new kernel fails (e.g. it panics), you can specify that GRUB should try
+the new kernel only once and boot the old kernel after that.
+
+ First, modify your configuration file. Here is an example:
+
+ default saved # This is important!!!
+ timeout 10
+
+ title the old kernel
+ root (hd0,0)
+ kernel /old_kernel
+ savedefault
+
+ title the new kernel
+ root (hd0,0)
+ kernel /new_kernel
+ savedefault 0 # This is important!!!
+
+ Note that this configuration file uses `default saved' (*note
+default::) at the head and `savedefault 0' (*note savedefault::) in the
+entry for the new kernel. This means that GRUB boots a saved entry by
+default, and booting the entry for the new kernel saves `0' as the
+saved entry.
+
+ With this configuration file, after all, GRUB always tries to boot
+the old kernel after it booted the new one, because `0' is the entry of
+`the old kernel'.
+
+ The next step is to tell GRUB to boot the new kernel at next boot
+time. For this, execute `grub-set-default' (*note Invoking
+grub-set-default::):
+
+ # grub-set-default 1
+
+ This command sets the saved entry to `1', that is, to the new kernel.
+
+ This method is useful, but still not very robust, because GRUB stops
+booting, if there is any error in the boot entry, such that the new
+kernel has an invalid executable format. Thus, it it even better to use
+the "fallback" mechanism of GRUB. Look at next subsection for this
+feature.
+
+4.3.2 Booting fallback systems
+------------------------------
+
+GRUB supports a fallback mechanism of booting one or more other entries
+if a default boot entry fails. You can specify multiple fallback
+entries if you wish.
+
+ Suppose that you have three systems, `A', `B' and `C'. `A' is a
+system which you want to boot by default. `B' is a backup system which
+is supposed to boot safely. `C' is another backup system which is used
+in case where `B' is broken.
+
+ Then you may want GRUB to boot the first system which is bootable
+among `A', `B' and `C'. A configuration file can be written in this way:
+
+ default saved # This is important!!!
+ timeout 10
+ fallback 1 2 # This is important!!!
+
+ title A
+ root (hd0,0)
+ kernel /kernel
+ savedefault fallback # This is important!!!
+
+ title B
+ root (hd1,0)
+ kernel /kernel
+ savedefault fallback # This is important!!!
+
+ title C
+ root (hd2,0)
+ kernel /kernel
+ savedefault
+
+ Note that `default saved' (*note default::), `fallback 1 2' and
+`savedefault fallback' are used. GRUB will boot a saved entry by
+default and save a fallback entry as next boot entry with this
+configuration.
+
+ When GRUB tries to boot `A', GRUB saves `1' as next boot entry,
+because the command `fallback' specifies that `1' is the first fallback
+entry. The entry `1' is `B', so GRUB will try to boot `B' at next boot
+time.
+
+ Likewise, when GRUB tries to boot `B', GRUB saves `2' as next boot
+entry, because `fallback' specifies `2' as next fallback entry. This
+makes sure that GRUB will boot `C' after booting `B'.
+
+ It is noteworthy that GRUB uses fallback entries both when GRUB
+itself fails in booting an entry and when `A' or `B' fails in starting
+up your system. So this solution ensures that your system is started
+even if GRUB cannot find your kernel or if your kernel panics.
+
+ However, you need to run `grub-set-default' (*note Invoking
+grub-set-default::) when `A' starts correctly or you fix `A' after it
+crashes, since GRUB always sets next boot entry to a fallback entry.
+You should run this command in a startup script such as `rc.local' to
+boot `A' by default:
+
+ # grub-set-default 0
+
+ where `0' is the number of the boot entry for the system `A'.
+
+ If you want to see what is current default entry, you can look at the
+file `/boot/grub/default' (or `/grub/default' in some systems). Because
+this file is plain-text, you can just `cat' this file. But it is
+strongly recommended *not to modify this file directly*, because GRUB
+may fail in saving a default entry in this file, if you change this
+file in an unintended manner. Therefore, you should use
+`grub-set-default' when you need to change the default entry.
+
+5 Configuration
+***************
+
+You've probably noticed that you need to type several commands to boot
+your OS. There's a solution to that - GRUB provides a menu interface
+(*note Menu interface::) from which you can select an item (using arrow
+keys) that will do everything to boot an OS.
+
+ To enable the menu, you need a configuration file, `menu.lst' under
+the boot directory. We'll analyze an example file.
+
+ The file first contains some general settings, the menu interface
+related options. You can put these commands (*note Menu-specific
+commands::) before any of the items (starting with `title' (*note
+title::)).
+
+ #
+ # Sample boot menu configuration file
+ #
+
+ As you may have guessed, these lines are comments. Lines starting
+with a hash character (`#'), and blank lines, are ignored by GRUB.
+
+ # By default, boot the first entry.
+ default 0
+
+ The first entry (here, counting starts with number zero, not one!)
+will be the default choice.
+
+ # Boot automatically after 30 secs.
+ timeout 30
+
+ As the comment says, GRUB will boot automatically in 30 seconds,
+unless interrupted with a keypress.
+
+ # Fallback to the second entry.
+ fallback 1
+
+ If, for any reason, the default entry doesn't work, fall back to the
+second one (this is rarely used, for obvious reasons).
+
+ Note that the complete descriptions of these commands, which are menu
+interface specific, can be found in *Note Menu-specific commands::.
+Other descriptions can be found in *Note Commands::.
+
+ Now, on to the actual OS definitions. You will see that each entry
+begins with a special command, `title' (*note title::), and the action
+is described after it. Note that there is no command `boot' (*note
+boot::) at the end of each item. That is because GRUB automatically
+executes `boot' if it loads other commands successfully.
+
+ The argument for the command `title' is used to display a short
+title/description of the entry in the menu. Since `title' displays the
+argument as is, you can write basically anything there.
+
+ # For booting GNU/Hurd
+ title GNU/Hurd
+ root (hd0,0)
+ kernel /boot/gnumach.gz root=hd0s1
+ module /boot/serverboot.gz
+
+ This boots GNU/Hurd from the first hard disk.
+
+ # For booting GNU/Linux
+ title GNU/Linux
+ kernel (hd1,0)/vmlinuz root=/dev/hdb1
+
+ This boots GNU/Linux, but from the second hard disk.
+
+ # For booting Mach (getting kernel from floppy)
+ title Utah Mach4 multiboot
+ root (hd0,2)
+ pause Insert the diskette now^G!!
+ kernel (fd0)/boot/kernel root=hd0s3
+ module (fd0)/boot/bootstrap
+
+ This boots Mach with a kernel on a floppy, but the root filesystem at
+hd0s3. It also contains a `pause' line (*note pause::), which will
+cause GRUB to display a prompt and delay, before actually executing the
+rest of the commands and booting.
+
+ # For booting FreeBSD
+ title FreeBSD
+ root (hd0,2,a)
+ kernel /boot/loader
+
+ This item will boot FreeBSD kernel loaded from the `a' partition of
+the third PC slice of the first hard disk.
+
+ # For booting OS/2
+ title OS/2
+ root (hd0,1)
+ makeactive
+ # chainload OS/2 bootloader from the first sector
+ chainloader +1
+ # This is similar to "chainload", but loads a specific file
+ #chainloader /boot/chain.os2
+
+ This will boot OS/2, using a chain-loader (*note Chain-loading::).
+
+ # For booting Windows NT or Windows95
+ title Windows NT / Windows 95 boot menu
+ root (hd0,0)
+ makeactive
+ chainloader +1
+ # For loading DOS if Windows NT is installed
+ # chainload /bootsect.dos
+
+ The same as the above, but for Windows.
+
+ # For installing GRUB into the hard disk
+ title Install GRUB into the hard disk
+ root (hd0,0)
+ setup (hd0)
+
+ This will just (re)install GRUB onto the hard disk.
+
+ # Change the colors.
+ title Change the colors
+ color light-green/brown blink-red/blue
+
+ In the last entry, the command `color' is used (*note color::), to
+change the menu colors (try it!). This command is somewhat special,
+because it can be used both in the command-line and in the menu. GRUB
+has several such commands, see *Note General commands::.
+
+ We hope that you now understand how to use the basic features of
+GRUB. To learn more about GRUB, see the following chapters.
+
+6 Downloading OS images from a network
+**************************************
+
+Although GRUB is a disk-based boot loader, it does provide network
+support. To use the network support, you need to enable at least one
+network driver in the GRUB build process. For more information please
+see `netboot/README.netboot' in the source distribution.
+
+6.1 How to set up your network
+==============================
+
+GRUB requires a file server and optionally a server that will assign an
+IP address to the machine on which GRUB is running. For the former, only
+TFTP is supported at the moment. The latter is either BOOTP, DHCP or a
+RARP server(1) (*note General usage of network support-Footnote-1::).
+It is not necessary to run both the servers on one computer. How to
+configure these servers is beyond the scope of this document, so please
+refer to the manuals specific to those protocols/servers.
+
+ If you decided to use a server to assign an IP address, set up the
+server and run `bootp' (*note bootp::), `dhcp' (*note dhcp::) or `rarp'
+(*note rarp::) for BOOTP, DHCP or RARP, respectively. Each command will
+show an assigned IP address, a netmask, an IP address for your TFTP
+server and a gateway. If any of the addresses is wrong or it causes an
+error, probably the configuration of your servers isn't set up properly.
+
+ Otherwise, run `ifconfig', like this:
+
+ grub> ifconfig --address=192.168.110.23 --server=192.168.110.14
+
+ You can also use `ifconfig' in conjuction with `bootp', `dhcp' or
+`rarp' (e.g. to reassign the server address manually). *Note
+ifconfig::, for more details.
+
+ Finally, download your OS images from your network. The network can
+be accessed using the network drive `(nd)'. Everything else is very
+similar to the normal instructions (*note Booting::).
+
+ Here is an example:
+
+ grub> bootp
+ Probing... [NE*000]
+ NE2000 base ...
+ Address: 192.168.110.23 Netmask: 255.255.255.0
+ Server: 192.168.110.14 Gateway: 192.168.110.1
+
+ grub> root (nd)
+ grub> kernel /tftproot/gnumach.gz root=sd0s1
+ grub> module /tftproot/serverboot.gz
+ grub> boot
+
+ (1) RARP is not advised, since it cannot serve much information
+
+6.2 Booting from a network
+==========================
+
+It is sometimes very useful to boot from a network, especially when you
+use a machine which has no local disk. In this case, you need to obtain
+a kind of Net Boot ROM, such as a PXE ROM or a free software package
+like Etherboot. Such a Boot ROM first boots the machine, sets up the
+network card installed into the machine, and downloads a second stage
+boot image from the network. Then, the second image will try to boot an
+operating system actually from the network.
+
+ GRUB provides two second stage images, `nbgrub' and `pxegrub' (*note
+Images::). These images are the same as the normal Stage 2, except that
+they set up a network automatically, and try to load a configuration
+file from the network, if specified. The usage is very simple: If the
+machine has a PXE ROM, use `pxegrub'. If the machine has an NBI loader
+such as Etherboot, use `nbgrub'. There is no difference between them
+except their formats. Since the way to load a second stage image you
+want to use should be described in the manual on your Net Boot ROM,
+please refer to the manual, for more information.
+
+ However, there is one thing specific to GRUB. Namely, how to specify
+a configuration file in a BOOTP/DHCP server. For now, GRUB uses the tag
+`150', to get the name of a configuration file. The following is an
+example with a BOOTP configuration:
+
+ .allhost:hd=/tmp:bf=null:\
+ :ds=145.71.35.1 145.71.32.1:\
+ :sm=255.255.254.0:\
+ :gw=145.71.35.1:\
+ :sa=145.71.35.5:
+
+ foo:ht=1:ha=63655d0334a7:ip=145.71.35.127:\
+ :bf=/nbgrub:\
+ :tc=.allhost:\
+ :T150="(nd)/tftpboot/menu.lst.foo":
+
+ Note that you should specify the drive name `(nd)' in the name of
+the configuration file. This is because you might change the root drive
+before downloading the configuration from the TFTP server when the
+preset menu feature is used (*note Preset Menu::).
+
+ See the manual of your BOOTP/DHCP server for more information. The
+exact syntax should differ a little from the example.
+
+7 Using GRUB via a serial line
+******************************
+
+This chapter describes how to use the serial terminal support in GRUB.
+
+ If you have many computers or computers with no display/keyboard, it
+could be very useful to control the computers through serial
+communications. To connect one computer with another via a serial line,
+you need to prepare a null-modem (cross) serial cable, and you may need
+to have multiport serial boards, if your computer doesn't have extra
+serial ports. In addition, a terminal emulator is also required, such as
+minicom. Refer to a manual of your operating system, for more
+information.
+
+ As for GRUB, the instruction to set up a serial terminal is quite
+simple. First of all, make sure that you haven't specified the option
+`--disable-serial' to the configure script when you built your GRUB
+images. If you get them in binary form, probably they have serial
+terminal support already.
+
+ Then, initialize your serial terminal after GRUB starts up. Here is
+an example:
+
+ grub> serial --unit=0 --speed=9600
+ grub> terminal serial
+
+ The command `serial' initializes the serial unit 0 with the speed
+9600bps. The serial unit 0 is usually called `COM1', so, if you want to
+use COM2, you must specify `--unit=1' instead. This command accepts
+many other options, so please refer to *Note serial::, for more details.
+
+ The command `terminal' (*note terminal::) chooses which type of
+terminal you want to use. In the case above, the terminal will be a
+serial terminal, but you can also pass `console' to the command, as
+`terminal serial console'. In this case, a terminal in which you press
+any key will be selected as a GRUB terminal.
+
+ However, note that GRUB assumes that your terminal emulator is
+compatible with VT100 by default. This is true for most terminal
+emulators nowadays, but you should pass the option `--dumb' to the
+command if your terminal emulator is not VT100-compatible or implements
+few VT100 escape sequences. If you specify this option then GRUB
+provides you with an alternative menu interface, because the normal
+menu requires several fancy features of your terminal.
+
+8 Embedding a configuration file into GRUB
+******************************************
+
+GRUB supports a "preset menu" which is to be always loaded before
+starting. The preset menu feature is useful, for example, when your
+computer has no console but a serial cable. In this case, it is
+critical to set up the serial terminal as soon as possible, since you
+cannot see any message until the serial terminal begins to work. So it
+is good to run the commands `serial' (*note serial::) and `terminal'
+(*note terminal::) before anything else at the start-up time.
+
+ How the preset menu works is slightly complicated:
+
+ 1. GRUB checks if the preset menu feature is used, and loads the
+ preset menu, if available. This includes running commands and
+ reading boot entries, like an ordinary configuration file.
+
+ 2. GRUB checks if the configuration file is available. Note that this
+ check is performed *regardless of the existence of the preset
+ menu*. The configuration file is loaded even if the preset menu was
+ loaded.
+
+ 3. If the preset menu includes any boot entries, they are cleared when
+ the configuration file is loaded. It doesn't matter whether the
+ configuration file has any entries or no entry. The boot entries
+ in the preset menu are used only when GRUB fails in loading the
+ configuration file.
+
+ To enable the preset menu feature, you must rebuild GRUB specifying a
+file to the configure script with the option `--enable-preset-menu'.
+The file has the same semantics as normal configuration files (*note
+Configuration::).
+
+ Another point you should take care is that the diskless support
+(*note Diskless::) diverts the preset menu. Diskless images embed a
+preset menu to execute the command `bootp' (*note bootp::)
+automatically, unless you specify your own preset menu to the configure
+script. This means that you must put commands to initialize a network in
+the preset menu yourself, because diskless images don't set it up
+implicitly, when you use the preset menu explicitly.
+
+ Therefore, a typical preset menu used with diskless support would be
+like this:
+
+ # Set up the serial terminal, first of all.
+ serial --unit=0 --speed=19200
+ terminal --timeout=0 serial
+
+ # Initialize the network.
+ dhcp
+
+9 Protecting your computer from cracking
+****************************************
+
+You may be interested in how to prevent ordinary users from doing
+whatever they like, if you share your computer with other people. So
+this chapter describes how to improve the security of GRUB.
+
+ One thing which could be a security hole is that the user can do too
+many things with GRUB, because GRUB allows one to modify its
+configuration and run arbitrary commands at run-time. For example, the
+user can even read `/etc/passwd' in the command-line interface by the
+command `cat' (*note cat::). So it is necessary to disable all the
+interactive operations.
+
+ Thus, GRUB provides a "password" feature, so that only administrators
+can start the interactive operations (i.e. editing menu entries and
+entering the command-line interface). To use this feature, you need to
+run the command `password' in your configuration file (*note
+password::), like this:
+
+ password --md5 PASSWORD
+
+ If this is specified, GRUB disallows any interactive control, until
+you press the key <p> and enter a correct password. The option `--md5'
+tells GRUB that `PASSWORD' is in MD5 format. If it is omitted, GRUB
+assumes the `PASSWORD' is in clear text.
+
+ You can encrypt your password with the command `md5crypt' (*note
+md5crypt::). For example, run the grub shell (*note Invoking the grub
+shell::), and enter your password:
+
+ grub> md5crypt
+ Password: **********
+ Encrypted: $1$U$JK7xFegdxWH6VuppCUSIb.
+
+ Then, cut and paste the encrypted password to your configuration
+file.
+
+ Also, you can specify an optional argument to `password'. See this
+example:
+
+ password PASSWORD /boot/grub/menu-admin.lst
+
+ In this case, GRUB will load `/boot/grub/menu-admin.lst' as a
+configuration file when you enter the valid password.
+
+ Another thing which may be dangerous is that any user can choose any
+menu entry. Usually, this wouldn't be problematic, but you might want to
+permit only administrators to run some of your menu entries, such as an
+entry for booting an insecure OS like DOS.
+
+ GRUB provides the command `lock' (*note lock::). This command always
+fails until you enter the valid password, so you can use it, like this:
+
+ title Boot DOS
+ lock
+ rootnoverify (hd0,1)
+ makeactive
+ chainload +1
+
+ You should insert `lock' right after `title', because any user can
+execute commands in an entry until GRUB encounters `lock'.
+
+ You can also use the command `password' instead of `lock'. In this
+case the boot process will ask for the password and stop if it was
+entered incorrectly. Since the `password' takes its own PASSWORD
+argument this is useful if you want different passwords for different
+entries.
+
+10 GRUB image files
+*******************
+
+GRUB consists of several images: two essential stages, optional stages
+called "Stage 1.5", one image for bootable CD-ROM, and two network boot
+images. Here is a short overview of them. *Note Internals::, for more
+details.
+
+`stage1'
+ This is an essential image used for booting up GRUB. Usually, this
+ is embedded in an MBR or the boot sector of a partition. Because a
+ PC boot sector is 512 bytes, the size of this image is exactly 512
+ bytes.
+
+ All `stage1' must do is to load Stage 2 or Stage 1.5 from a local
+ disk. Because of the size restriction, `stage1' encodes the
+ location of Stage 2 (or Stage 1.5) in a block list format, so it
+ never understand any filesystem structure.
+
+`stage2'
+ This is the core image of GRUB. It does everything but booting up
+ itself. Usually, this is put in a filesystem, but that is not
+ required.
+
+`e2fs_stage1_5'
+`fat_stage1_5'
+`ffs_stage1_5'
+`jfs_stage1_5'
+`minix_stage1_5'
+`reiserfs_stage1_5'
+`vstafs_stage1_5'
+`xfs_stage1_5'
+ These are called "Stage 1.5", because they serve as a bridge
+ between `stage1' and `stage2', that is to say, Stage 1.5 is loaded
+ by Stage 1 and Stage 1.5 loads Stage 2. The difference between
+ `stage1' and `*_stage1_5' is that the former doesn't understand
+ any filesystem while the latter understands one filesystem (e.g.
+ `e2fs_stage1_5' understands ext2fs). So you can move the Stage 2
+ image to another location safely, even after GRUB has been
+ installed.
+
+ While Stage 2 cannot generally be embedded in a fixed area as the
+ size is so large, Stage 1.5 can be installed into the area right
+ after an MBR, or the boot loader area of a ReiserFS or a FFS.
+
+`stage2_eltorito'
+ This is a boot image for CD-ROMs using the "no emulation mode" in
+ El Torito specification. This is identical to Stage 2, except that
+ this boots up without Stage 1 and sets up a special drive `(cd)'.
+
+`nbgrub'
+ This is a network boot image for the Network Image Proposal used
+ by some network boot loaders, such as Etherboot. This is mostly
+ the same as Stage 2, but it also sets up a network and loads a
+ configuration file from the network.
+
+`pxegrub'
+ This is another network boot image for the Preboot Execution
+ Environment used by several Netboot ROMs. This is identical to
+ `nbgrub', except for the format.
+
+11 Filesystem syntax and semantics
+**********************************
+
+GRUB uses a special syntax for specifying disk drives which can be
+accessed by BIOS. Because of BIOS limitations, GRUB cannot distinguish
+between IDE, ESDI, SCSI, or others. You must know yourself which BIOS
+device is equivalent to which OS device. Normally, that will be clear if
+you see the files in a device or use the command `find' (*note find::).
+
+11.1 How to specify devices
+===========================
+
+The device syntax is like this:
+
+ `(DEVICE[,PART-NUM][,BSD-SUBPART-LETTER])'
+
+ `[]' means the parameter is optional. DEVICE should be either `fd'
+or `hd' followed by a digit, like `fd0'. But you can also set DEVICE
+to a hexadecimal or a decimal number which is a BIOS drive number, so
+the following are equivalent:
+
+ (hd0)
+ (0x80)
+ (128)
+
+ PART-NUM represents the partition number of DEVICE, starting from
+zero for primary partitions and from four for extended partitions, and
+BSD-SUBPART-LETTER represents the BSD disklabel subpartition, such as
+`a' or `e'.
+
+ A shortcut for specifying BSD subpartitions is
+`(DEVICE,BSD-SUBPART-LETTER)', in this case, GRUB searches for the
+first PC partition containing a BSD disklabel, then finds the
+subpartition BSD-SUBPART-LETTER. Here is an example:
+
+ (hd0,a)
+
+ The syntax `(hd0)' represents using the entire disk (or the MBR when
+installing GRUB), while the syntax `(hd0,0)' represents using the first
+partition of the disk (or the boot sector of the partition when
+installing GRUB).
+
+ If you enabled the network support, the special drive, `(nd)', is
+also available. Before using the network drive, you must initialize the
+network. *Note Network::, for more information.
+
+ If you boot GRUB from a CD-ROM, `(cd)' is available. *Note Making a
+GRUB bootable CD-ROM::, for details.
+
+11.2 How to specify files
+=========================
+
+There are two ways to specify files, by "absolute file name" and by
+"block list".
+
+ An absolute file name resembles a Unix absolute file name, using `/'
+for the directory separator (not `\' as in DOS). One example is
+`(hd0,0)/boot/grub/menu.lst'. This means the file `/boot/grub/menu.lst'
+in the first partition of the first hard disk. If you omit the device
+name in an absolute file name, GRUB uses GRUB's "root device"
+implicitly. So if you set the root device to, say, `(hd1,0)' by the
+command `root' (*note root::), then `/boot/kernel' is the same as
+`(hd1,0)/boot/kernel'.
+
+11.3 How to specify block lists
+===============================
+
+A block list is used for specifying a file that doesn't appear in the
+filesystem, like a chainloader. The syntax is
+`[OFFSET]+LENGTH[,[OFFSET]+LENGTH]...'. Here is an example:
+
+ `0+100,200+1,300+300'
+
+ This represents that GRUB should read blocks 0 through 99, block 200,
+and blocks 300 through 599. If you omit an offset, then GRUB assumes
+the offset is zero.
+
+ Like the file name syntax (*note File name syntax::), if a blocklist
+does not contain a device name, then GRUB uses GRUB's "root device". So
+`(hd0,1)+1' is the same as `+1' when the root device is `(hd0,1)'.
+
+12 GRUB's user interface
+************************
+
+GRUB has both a simple menu interface for choosing preset entries from a
+configuration file, and a highly flexible command-line for performing
+any desired combination of boot commands.
+
+ GRUB looks for its configuration file as soon as it is loaded. If one
+is found, then the full menu interface is activated using whatever
+entries were found in the file. If you choose the "command-line" menu
+option, or if the configuration file was not found, then GRUB drops to
+the command-line interface.
+
+12.1 The flexible command-line interface
+========================================
+
+The command-line interface provides a prompt and after it an editable
+text area much like a command-line in Unix or DOS. Each command is
+immediately executed after it is entered(1) (*note Command-line
+interface-Footnote-1::). The commands (*note Command-line and menu
+entry commands::) are a subset of those available in the configuration
+file, used with exactly the same syntax.
+
+ Cursor movement and editing of the text on the line can be done via a
+subset of the functions available in the Bash shell:
+
+<C-f>
+<PC right key>
+ Move forward one character.
+
+<C-b>
+<PC left key>
+ Move back one character.
+
+<C-a>
+<HOME>
+ Move to the start of the line.
+
+<C-e>
+<END>
+ Move the the end of the line.
+
+<C-d>
+<DEL>
+ Delete the character underneath the cursor.
+
+<C-h>
+<BS>
+ Delete the character to the left of the cursor.
+
+<C-k>
+ Kill the text from the current cursor position to the end of the
+ line.
+
+<C-u>
+ Kill backward from the cursor to the beginning of the line.
+
+<C-y>
+ Yank the killed text back into the buffer at the cursor.
+
+<C-p>
+<PC up key>
+ Move up through the history list.
+
+<C-n>
+<PC down key>
+ Move down through the history list.
+
+ When typing commands interactively, if the cursor is within or before
+the first word in the command-line, pressing the <TAB> key (or <C-i>)
+will display a listing of the available commands, and if the cursor is
+after the first word, the `<TAB>' will provide a completion listing of
+disks, partitions, and file names depending on the context. Note that
+to obtain a list of drives, one must open a parenthesis, as `root ('.
+
+ Note that you cannot use the completion functionality in the TFTP
+filesystem. This is because TFTP doesn't support file name listing for
+the security.
+
+ (1) However, this behavior will be changed in the future version, in
+a user-invisible way.
+
+12.2 The simple menu interface
+==============================
+
+The menu interface is quite easy to use. Its commands are both
+reasonably intuitive and described on screen.
+
+ Basically, the menu interface provides a list of "boot entries" to
+the user to choose from. Use the arrow keys to select the entry of
+choice, then press <RET> to run it. An optional timeout is available
+to boot the default entry (the first one if not set), which is aborted
+by pressing any key.
+
+ Commands are available to enter a bare command-line by pressing <c>
+(which operates exactly like the non-config-file version of GRUB, but
+allows one to return to the menu if desired by pressing <ESC>) or to
+edit any of the "boot entries" by pressing <e>.
+
+ If you protect the menu interface with a password (*note Security::),
+all you can do is choose an entry by pressing <RET>, or press <p> to
+enter the password.
+
+12.3 Editing a menu entry
+=========================
+
+The menu entry editor looks much like the main menu interface, but the
+lines in the menu are individual commands in the selected entry instead
+of entry names.
+
+ If an <ESC> is pressed in the editor, it aborts all the changes made
+to the configuration entry and returns to the main menu interface.
+
+ When a particular line is selected, the editor places the user in a
+special version of the GRUB command-line to edit that line. When the
+user hits <RET>, GRUB replaces the line in question in the boot entry
+with the changes (unless it was aborted via <ESC>, in which case the
+changes are thrown away).
+
+ If you want to add a new line to the menu entry, press <o> if adding
+a line after the current line or press <O> if before the current line.
+
+ To delete a line, hit the key <d>. Although GRUB unfortunately does
+not support "undo", you can do almost the same thing by just returning
+to the main menu.
+
+12.4 The hidden menu interface
+==============================
+
+When your terminal is dumb or you request GRUB to hide the menu
+interface explicitly with the command `hiddenmenu' (*note
+hiddenmenu::), GRUB doesn't show the menu interface (*note Menu
+interface::) and automatically boots the default entry, unless
+interrupted by pressing <ESC>.
+
+ When you interrupt the timeout and your terminal is dumb, GRUB falls
+back to the command-line interface (*note Command-line interface::).
+
+13 The list of available commands
+*********************************
+
+In this chapter, we list all commands that are available in GRUB.
+
+ Commands belong to different groups. A few can only be used in the
+global section of the configuration file (or "menu"); most of them can
+be entered on the command-line and can be used either anywhere in the
+menu or specifically in the menu entries.
+
+13.1 The list of commands for the menu only
+===========================================
+
+The semantics used in parsing the configuration file are the following:
+
+ * The menu-specific commands have to be used before any others.
+
+ * The files _must_ be in plain-text format.
+
+ * `#' at the beginning of a line in a configuration file means it is
+ only a comment.
+
+ * Options are separated by spaces.
+
+ * All numbers can be either decimal or hexadecimal. A hexadecimal
+ number must be preceded by `0x', and is case-insensitive.
+
+ * Extra options or text at the end of the line are ignored unless
+ otherwise specified.
+
+ * Unrecognized commands are added to the current entry, except
+ before entries start, where they are ignored.
+
+ These commands can only be used in the menu:
+
+13.1.1 default
+--------------
+
+ -- Command: default num
+ Set the default entry to the entry number NUM. Numbering starts
+ from 0, and the entry number 0 is the default if the command is not
+ used.
+
+ You can specify `saved' instead of a number. In this case, the
+ default entry is the entry saved with the command `savedefault'.
+ *Note savedefault::, for more information.
+
+13.1.2 fallback
+---------------
+
+ -- Command: fallback num...
+ Go into unattended boot mode: if the default boot entry has any
+ errors, instead of waiting for the user to do something,
+ immediately start over using the NUM entry (same numbering as the
+ `default' command (*note default::)). This obviously won't help if
+ the machine was rebooted by a kernel that GRUB loaded. You can
+ specify multiple fallback entry numbers.
+
+13.1.3 hiddenmenu
+-----------------
+
+ -- Command: hiddenmenu
+ Don't display the menu. If the command is used, no menu will be
+ displayed on the control terminal, and the default entry will be
+ booted after the timeout expired. The user can still request the
+ menu to be displayed by pressing <ESC> before the timeout expires.
+ See also *Note Hidden menu interface::.
+
+13.1.4 timeout
+--------------
+
+ -- Command: timeout sec
+ Set a timeout, in SEC seconds, before automatically booting the
+ default entry (normally the first entry defined).
+
+13.1.5 title
+------------
+
+ -- Command: title name ...
+ Start a new boot entry, and set its name to the contents of the
+ rest of the line, starting with the first non-space character.
+
+13.2 The list of general commands
+=================================
+
+Commands usable anywhere in the menu and in the command-line.
+
+13.2.1 bootp
+------------
+
+ -- Command: bootp [`--with-configfile']
+ Initialize a network device via the "BOOTP" protocol. This command
+ is only available if GRUB is compiled with netboot support. See
+ also *Note Network::.
+
+ If you specify `--with-configfile' to this command, GRUB will
+ fetch and load a configuration file specified by your BOOTP server
+ with the vendor tag `150'.
+
+13.2.2 color
+------------
+
+ -- Command: color normal [highlight]
+ Change the menu colors. The color NORMAL is used for most lines in
+ the menu (*note Menu interface::), and the color HIGHLIGHT is used
+ to highlight the line where the cursor points. If you omit
+ HIGHLIGHT, then the inverted color of NORMAL is used for the
+ highlighted line. The format of a color is
+ `FOREGROUND/BACKGROUND'. FOREGROUND and BACKGROUND are symbolic
+ color names. A symbolic color name must be one of these:
+
+ * black
+
+ * blue
+
+ * green
+
+ * cyan
+
+ * red
+
+ * magenta
+
+ * brown
+
+ * light-gray
+
+ *These below can be specified only for the foreground.*
+
+ * dark-gray
+
+ * light-blue
+
+ * light-green
+
+ * light-cyan
+
+ * light-red
+
+ * light-magenta
+
+ * yellow
+
+ * white
+
+ But only the first eight names can be used for BACKGROUND. You can
+ prefix `blink-' to FOREGROUND if you want a blinking foreground
+ color.
+
+ This command can be used in the configuration file and on the
+ command line, so you may write something like this in your
+ configuration file:
+
+ # Set default colors.
+ color light-gray/blue black/light-gray
+
+ # Change the colors.
+ title OS-BS like
+ color magenta/blue black/magenta
+
+13.2.3 device
+-------------
+
+ -- Command: device drive file
+ In the grub shell, specify the file FILE as the actual drive for a
+ BIOS drive DRIVE. You can use this command to create a disk image,
+ and/or to fix the drives guessed by GRUB when GRUB fails to
+ determine them correctly, like this:
+
+ grub> device (fd0) /floppy-image
+ grub> device (hd0) /dev/sd0
+
+ This command can be used only in the grub shell (*note Invoking
+ the grub shell::).
+
+13.2.4 dhcp
+-----------
+
+ -- Command: dhcp [-with-configfile]
+ Initialize a network device via the "DHCP" protocol. Currently,
+ this command is just an alias for `bootp', since the two protocols
+ are very similar. This command is only available if GRUB is
+ compiled with netboot support. See also *Note Network::.
+
+ If you specify `--with-configfile' to this command, GRUB will
+ fetch and load a configuration file specified by your DHCP server
+ with the vendor tag `150'.
+
+13.2.5 hide
+-----------
+
+ -- Command: hide partition
+ Hide the partition PARTITION by setting the "hidden" bit in its
+ partition type code. This is useful only when booting DOS or
+ Windows and multiple primary FAT partitions exist in one disk. See
+ also *Note DOS/Windows::.
+
+13.2.6 ifconfig
+---------------
+
+ -- Command: ifconfig [`--server=server'] [`--gateway=gateway']
+ [`--mask=mask'] [`--address=address']
+ Configure the IP address, the netmask, the gateway, and the server
+ address of a network device manually. The values must be in dotted
+ decimal format, like `192.168.11.178'. The order of the options is
+ not important. This command shows current network configuration,
+ if no option is specified. See also *Note Network::.
+
+13.2.7 pager
+------------
+
+ -- Command: pager [flag]
+ Toggle or set the state of the internal pager. If FLAG is `on',
+ the internal pager is enabled. If FLAG is `off', it is disabled.
+ If no argument is given, the state is toggled.
+
+13.2.8 partnew
+--------------
+
+ -- Command: partnew part type from len
+ Create a new primary partition. PART is a partition specification
+ in GRUB syntax (*note Naming convention::); TYPE is the partition
+ type and must be a number in the range `0-0xff'; FROM is the
+ starting address and LEN is the length, both in sector units.
+
+13.2.9 parttype
+---------------
+
+ -- Command: parttype part type
+ Change the type of an existing partition. PART is a partition
+ specification in GRUB syntax (*note Naming convention::); TYPE is
+ the new partition type and must be a number in the range 0-0xff.
+
+13.2.10 password
+----------------
+
+ -- Command: password [`--md5'] passwd [new-config-file]
+ If used in the first section of a menu file, disable all
+ interactive editing control (menu entry editor and command-line)
+ and entries protected by the command `lock'. If the password
+ PASSWD is entered, it loads the NEW-CONFIG-FILE as a new config
+ file and restarts the GRUB Stage 2, if NEW-CONFIG-FILE is
+ specified. Otherwise, GRUB will just unlock the privileged
+ instructions. You can also use this command in the script
+ section, in which case it will ask for the password, before
+ continuing. The option `--md5' tells GRUB that PASSWD is
+ encrypted with `md5crypt' (*note md5crypt::).
+
+13.2.11 rarp
+------------
+
+ -- Command: rarp
+ Initialize a network device via the "RARP" protocol. This command
+ is only available if GRUB is compiled with netboot support. See
+ also *Note Network::.
+
+13.2.12 serial
+--------------
+
+ -- Command: serial [`--unit=unit'] [`--port=port'] [`--speed=speed']
+ [`--word=word'] [`--parity=parity'] [`--stop=stop']
+ [`--device=dev']
+ Initialize a serial device. UNIT is a number in the range 0-3
+ specifying which serial port to use; default is 0, which
+ corresponds to the port often called COM1. PORT is the I/O port
+ where the UART is to be found; if specified it takes precedence
+ over UNIT. SPEED is the transmission speed; default is 9600. WORD
+ and STOP are the number of data bits and stop bits. Data bits must
+ be in the range 5-8 and stop bits must be 1 or 2. Default is 8 data
+ bits and one stop bit. PARITY is one of `no', `odd', `even' and
+ defaults to `no'. The option `--device' can only be used in the
+ grub shell and is used to specify the tty device to be used in the
+ host operating system (*note Invoking the grub shell::).
+
+ The serial port is not used as a communication channel unless the
+ `terminal' command is used (*note terminal::).
+
+ This command is only available if GRUB is compiled with serial
+ support. See also *Note Serial terminal::.
+
+13.2.13 setkey
+--------------
+
+ -- Command: setkey [to_key from_key]
+ Change the keyboard map. The key FROM_KEY is mapped to the key
+ TO_KEY. If no argument is specified, reset key mappings. Note that
+ this command _does not_ exchange the keys. If you want to exchange
+ the keys, run this command again with the arguments exchanged,
+ like this:
+
+ grub> setkey capslock control
+ grub> setkey control capslock
+
+ A key must be an alphabet letter, a digit, or one of these symbols:
+ `escape', `exclam', `at', `numbersign', `dollar', `percent',
+ `caret', `ampersand', `asterisk', `parenleft', `parenright',
+ `minus', `underscore', `equal', `plus', `backspace', `tab',
+ `bracketleft', `braceleft', `bracketright', `braceright', `enter',
+ `control', `semicolon', `colon', `quote', `doublequote',
+ `backquote', `tilde', `shift', `backslash', `bar', `comma',
+ `less', `period', `greater', `slash', `question', `alt', `space',
+ `capslock', `FX' (`X' is a digit), and `delete'. This table
+ describes to which character each of the symbols corresponds:
+
+ `exclam'
+ `!'
+
+ `at'
+ `@'
+
+ `numbersign'
+ `#'
+
+ `dollar'
+ `$'
+
+ `percent'
+ `%'
+
+ `caret'
+ `^'
+
+ `ampersand'
+ `&'
+
+ `asterisk'
+ `*'
+
+ `parenleft'
+ `('
+
+ `parenright'
+ `)'
+
+ `minus'
+ `-'
+
+ `underscore'
+ `_'
+
+ `equal'
+ `='
+
+ `plus'
+ `+'
+
+ `bracketleft'
+ `['
+
+ `braceleft'
+ `{'
+
+ `bracketright'
+ `]'
+
+ `braceright'
+ `}'
+
+ `semicolon'
+ `;'
+
+ `colon'
+ `:'
+
+ `quote'
+ `''
+
+ `doublequote'
+ `"'
+
+ `backquote'
+ ``'
+
+ `tilde'
+ `~'
+
+ `backslash'
+ `\'
+
+ `bar'
+ `|'
+
+ `comma'
+ `,'
+
+ `less'
+ `<'
+
+ `period'
+ `.'
+
+ `greater'
+ `>'
+
+ `slash'
+ `/'
+
+ `question'
+ `?'
+
+ `space'
+ ` '
+
+13.2.14 terminal
+----------------
+
+ -- Command: terminal [`--dumb'] [`--no-echo'] [`--no-edit']
+ [`--timeout=secs'] [`--lines=lines'] [`--silent'] [`console']
+ [`serial'] [`hercules']
+ Select a terminal for user interaction. The terminal is assumed to
+ be VT100-compatible unless `--dumb' is specified. If both
+ `console' and `serial' are specified, then GRUB will use the one
+ where a key is entered first or the first when the timeout
+ expires. If neither are specified, the current setting is
+ reported. This command is only available if GRUB is compiled with
+ serial support. See also *Note Serial terminal::.
+
+ This may not make sense for most users, but GRUB supports Hercules
+ console as well. Hercules console is usable like the ordinary
+ console, and the usage is quite similar to that for serial
+ terminals: specify `hercules' as the argument.
+
+ The option `--lines' defines the number of lines in your terminal,
+ and it is used for the internal pager function. If you don't
+ specify this option, the number is assumed as 24.
+
+ The option `--silent' suppresses the message to prompt you to hit
+ any key. This might be useful if your system has no terminal
+ device.
+
+ The option `--no-echo' has GRUB not to echo back input characters.
+ This implies the option `--no-edit'.
+
+ The option `--no-edit' disables the BASH-like editing feature.
+
+13.2.15 terminfo
+----------------
+
+ -- Command: terminfo `--name=name' `--cursor-address=seq'
+ [`--clear-screen=seq'] [`--enter-standout-mode=seq']
+ [`--exit-standout-mode=seq']
+ Define the capabilities of your terminal. Use this command to
+ define escape sequences, if it is not vt100-compatible. You may
+ use `\e' for <ESC> and `^X' for a control character.
+
+ You can use the utility `grub-terminfo' to generate appropriate
+ arguments to this command. *Note Invoking grub-terminfo::.
+
+ If no option is specified, the current settings are printed.
+
+13.2.16 tftpserver
+------------------
+
+ -- Command: tftpserver ipaddr
+ *Caution:* This command exists only for backward compatibility.
+ Use `ifconfig' (*note ifconfig::) instead.
+
+ Override a TFTP server address returned by a BOOTP/DHCP/RARP
+ server. The argument IPADDR must be in dotted decimal format, like
+ `192.168.0.15'. This command is only available if GRUB is compiled
+ with netboot support. See also *Note Network::.
+
+13.2.17 unhide
+--------------
+
+ -- Command: unhide partition
+ Unhide the partition PARTITION by clearing the "hidden" bit in its
+ partition type code. This is useful only when booting DOS or
+ Windows and multiple primary partitions exist on one disk. See also
+ *Note DOS/Windows::.
+
+13.3 The list of command-line and menu entry commands
+=====================================================
+
+These commands are usable in the command-line and in menu entries. If
+you forget a command, you can run the command `help' (*note help::).
+
+13.3.1 blocklist
+----------------
+
+ -- Command: blocklist file
+ Print the block list notation of the file FILE. *Note Block list
+ syntax::.
+
+13.3.2 boot
+-----------
+
+ -- Command: boot
+ Boot the OS or chain-loader which has been loaded. Only necessary
+ if running the fully interactive command-line (it is implicit at
+ the end of a menu entry).
+
+13.3.3 cat
+----------
+
+ -- Command: cat file
+ Display the contents of the file FILE. This command may be useful
+ to remind you of your OS's root partition:
+
+ grub> cat /etc/fstab
+
+13.3.4 chainloader
+------------------
+
+ -- Command: chainloader [`--force'] file
+ Load FILE as a chain-loader. Like any other file loaded by the
+ filesystem code, it can use the blocklist notation to grab the
+ first sector of the current partition with `+1'. If you specify the
+ option `--force', then load FILE forcibly, whether it has a
+ correct signature or not. This is required when you want to load a
+ defective boot loader, such as SCO UnixWare 7.1 (*note SCO
+ UnixWare::).
+
+13.3.5 cmp
+----------
+
+ -- Command: cmp file1 file2
+ Compare the file FILE1 with the file FILE2. If they differ in
+ size, print the sizes like this:
+
+ Differ in size: 0x1234 [foo], 0x4321 [bar]
+
+ If the sizes are equal but the bytes at an offset differ, then
+ print the bytes like this:
+
+ Differ at the offset 777: 0xbe [foo], 0xef [bar]
+
+ If they are completely identical, nothing will be printed.
+
+13.3.6 configfile
+-----------------
+
+ -- Command: configfile file
+ Load FILE as a configuration file.
+
+13.3.7 debug
+------------
+
+ -- Command: debug
+ Toggle debug mode (by default it is off). When debug mode is on,
+ some extra messages are printed to show disk activity. This global
+ debug flag is mainly useful for GRUB developers when testing new
+ code.
+
+13.3.8 displayapm
+-----------------
+
+ -- Command: displayapm
+ Display APM BIOS information.
+
+13.3.9 displaymem
+-----------------
+
+ -- Command: displaymem
+ Display what GRUB thinks the system address space map of the
+ machine is, including all regions of physical RAM installed. GRUB's
+ "upper/lower memory" display uses the standard BIOS interface for
+ the available memory in the first megabyte, or "lower memory", and
+ a synthesized number from various BIOS interfaces of the memory
+ starting at 1MB and going up to the first chipset hole for "upper
+ memory" (the standard PC "upper memory" interface is limited to
+ reporting a maximum of 64MB).
+
+13.3.10 embed
+-------------
+
+ -- Command: embed stage1_5 device
+ Embed the Stage 1.5 STAGE1_5 in the sectors after the MBR if
+ DEVICE is a drive, or in the "boot loader" area if DEVICE is a FFS
+ partition or a ReiserFS partition.(1) (*note embed-Footnote-1::)
+ Print the number of sectors which STAGE1_5 occupies, if successful.
+
+ Usually, you don't need to run this command directly. *Note
+ setup::.
+
+ (1) The latter feature has not been implemented yet.
+
+13.3.11 find
+------------
+
+ -- Command: find filename
+ Search for the file name FILENAME in all mountable partitions and
+ print the list of the devices which contain the file. The file
+ name FILENAME should be an absolute file name like
+ `/boot/grub/stage1'.
+
+13.3.12 fstest
+--------------
+
+ -- Command: fstest
+ Toggle filesystem test mode. Filesystem test mode, when turned
+ on, prints out data corresponding to all the device reads and what
+ values are being sent to the low-level routines. The format is
+ `<PARTITION-OFFSET-SECTOR, BYTE-OFFSET, BYTE-LENGTH>' for
+ high-level reads inside a partition, and `[DISK-OFFSET-SECTOR]'
+ for low-level sector requests from the disk. Filesystem test mode
+ is turned off by any use of the `install' (*note install::) or
+ `testload' (*note testload::) commands.
+
+13.3.13 geometry
+----------------
+
+ -- Command: geometry drive [cylinder head sector [total_sector]]
+ Print the information for the drive DRIVE. In the grub shell, you
+ can set the geometry of the drive arbitrarily. The number of
+ cylinders, the number of heads, the number of sectors and the
+ number of total sectors are set to CYLINDER, HEAD, SECTOR and
+ TOTAL_SECTOR, respectively. If you omit TOTAL_SECTOR, then it will
+ be calculated based on the C/H/S values automatically.
+
+13.3.14 halt
+------------
+
+ -- Command: halt `--no-apm'
+ The command halts the computer. If the `--no-apm' option is
+ specified, no APM BIOS call is performed. Otherwise, the computer
+ is shut down using APM.
+
+13.3.15 help
+------------
+
+ -- Command: help `--all' [pattern ...]
+ Display helpful information about builtin commands. If you do not
+ specify PATTERN, this command shows short descriptions of most of
+ available commands. If you specify the option `--all' to this
+ command, short descriptions of rarely used commands (such as *Note
+ testload::) are displayed as well.
+
+ If you specify any PATTERNS, it displays longer information about
+ each of the commands which match those PATTERNS.
+
+13.3.16 impsprobe
+-----------------
+
+ -- Command: impsprobe
+ Probe the Intel Multiprocessor Specification 1.1 or 1.4
+ configuration table and boot the various CPUs which are found into
+ a tight loop. This command can be used only in the Stage 2, but
+ not in the grub shell.
+
+13.3.17 initrd
+--------------
+
+ -- Command: initrd file ...
+ Load an initial ramdisk for a Linux format boot image and set the
+ appropriate parameters in the Linux setup area in memory. See also
+ *Note GNU/Linux::.
+
+13.3.18 install
+---------------
+
+ -- Command: install [`--force-lba'] [`--stage2=os_stage2_file']
+ stage1_file [`d'] dest_dev stage2_file [addr] [`p']
+ [config_file] [real_config_file]
+ This command is fairly complex, and you should not use this command
+ unless you are familiar with GRUB. Use `setup' (*note setup::)
+ instead.
+
+ In short, it will perform a full install presuming the Stage 2 or
+ Stage 1.5(1) (*note install-Footnote-1::) is in its final install
+ location.
+
+ In slightly more detail, it will load STAGE1_FILE, validate that
+ it is a GRUB Stage 1 of the right version number, install in it a
+ blocklist for loading STAGE2_FILE as a Stage 2. If the option `d'
+ is present, the Stage 1 will always look for the actual disk
+ STAGE2_FILE was installed on, rather than using the booting drive.
+ The Stage 2 will be loaded at address ADDR, which must be `0x8000'
+ for a true Stage 2, and `0x2000' for a Stage 1.5. If ADDR is not
+ present, GRUB will determine the address automatically. It then
+ writes the completed Stage 1 to the first block of the device
+ DEST_DEV. If the options `p' or CONFIG_FILE are present, then it
+ reads the first block of stage2, modifies it with the values of
+ the partition STAGE2_FILE was found on (for `p') or places the
+ string CONFIG_FILE into the area telling the stage2 where to look
+ for a configuration file at boot time. Likewise, if
+ REAL_CONFIG_FILE is present and STAGE2_FILE is a Stage 1.5, then
+ the Stage 2 CONFIG_FILE is patched with the configuration file
+ name REAL_CONFIG_FILE. This command preserves the DOS BPB (and for
+ hard disks, the partition table) of the sector the Stage 1 is to
+ be installed into.
+
+ *Caution:* Several buggy BIOSes don't pass a booting drive
+ properly when booting from a hard disk drive. Therefore, you will
+ unfortunately have to specify the option `d', whether your Stage2
+ resides at the booting drive or not, if you have such a BIOS. We
+ know these are defective in this way:
+
+
+ Fujitsu LifeBook 400 BIOS version 31J0103A
+
+
+ HP Vectra XU 6/200 BIOS version GG.06.11
+
+ *Caution2:* A number of BIOSes don't return a correct LBA support
+ bitmap even if they do have the support. So GRUB provides a
+ solution to ignore the wrong bitmap, that is, the option
+ `--force-lba'. Don't use this option if you know that your BIOS
+ doesn't have LBA support.
+
+ *Caution3:* You must specify the option `--stage2' in the grub
+ shell, if you cannot unmount the filesystem where your stage2 file
+ resides. The argument should be the file name in your operating
+ system.
+
+ (1) They're loaded the same way, so we will refer to the Stage 1.5
+as a Stage 2 from now on.
+
+13.3.19 ioprobe
+---------------
+
+ -- Command: ioprobe drive
+ Probe I/O ports used for the drive DRIVE. This command will list
+ the I/O ports on the screen. For technical information, *Note
+ Internals::.
+
+13.3.20 kernel
+--------------
+
+ -- Command: kernel [`--type=type'] [`--no-mem-option'] file ...
+ Attempt to load the primary boot image (Multiboot a.out or ELF,
+ Linux zImage or bzImage, FreeBSD a.out, NetBSD a.out, etc.) from
+ FILE. The rest of the line is passed verbatim as the "kernel
+ command-line". Any modules must be reloaded after using this
+ command.
+
+ This command also accepts the option `--type' so that you can
+ specify the kernel type of FILE explicitly. The argument TYPE must
+ be one of these: `netbsd', `freebsd', `openbsd', `linux',
+ `biglinux', and `multiboot'. However, you need to specify it only
+ if you want to load a NetBSD ELF kernel, because GRUB can
+ automatically determine a kernel type in the other cases, quite
+ safely.
+
+ The option `--no-mem-option' is effective only for Linux. If the
+ option is specified, GRUB doesn't pass the option `mem=' to the
+ kernel. This option is implied for Linux kernels 2.4.18 and newer.
+
+13.3.21 lock
+------------
+
+ -- Command: lock
+ Prevent normal users from executing arbitrary menu entries. You
+ must use the command `password' if you really want this command to
+ be useful (*note password::).
+
+ This command is used in a menu, as shown in this example:
+
+ title This entry is too dangerous to be executed by normal users
+ lock
+ root (hd0,a)
+ kernel /no-security-os
+
+ See also *Note Security::.
+
+13.3.22 makeactive
+------------------
+
+ -- Command: makeactive
+ Set the active partition on the root disk to GRUB's root device.
+ This command is limited to _primary_ PC partitions on a hard disk.
+
+13.3.23 map
+-----------
+
+ -- Command: map to_drive from_drive
+ Map the drive FROM_DRIVE to the drive TO_DRIVE. This is necessary
+ when you chain-load some operating systems, such as DOS, if such
+ an OS resides at a non-first drive. Here is an example:
+
+ grub> map (hd0) (hd1)
+ grub> map (hd1) (hd0)
+
+ The example exchanges the order between the first hard disk and the
+ second hard disk. See also *Note DOS/Windows::.
+
+13.3.24 md5crypt
+----------------
+
+ -- Command: md5crypt
+ Prompt to enter a password, and encrypt it in MD5 format. The
+ encrypted password can be used with the command `password' (*note
+ password::). See also *Note Security::.
+
+13.3.25 module
+--------------
+
+ -- Command: module file ...
+ Load a boot module FILE for a Multiboot format boot image (no
+ interpretation of the file contents are made, so the user of this
+ command must know what the kernel in question expects). The rest
+ of the line is passed as the "module command-line", like the
+ `kernel' command. You must load a Multiboot kernel image before
+ loading any module. See also *Note modulenounzip::.
+
+13.3.26 modulenounzip
+---------------------
+
+ -- Command: modulenounzip file ...
+ The same as `module' (*note module::), except that automatic
+ decompression is disabled.
+
+13.3.27 pause
+-------------
+
+ -- Command: pause message ...
+ Print the MESSAGE, then wait until a key is pressed. Note that
+ placing <^G> (ASCII code 7) in the message will cause the speaker
+ to emit the standard beep sound, which is useful when prompting
+ the user to change floppies.
+
+13.3.28 quit
+------------
+
+ -- Command: quit
+ Exit from the grub shell `grub' (*note Invoking the grub shell::).
+ This command can be used only in the grub shell.
+
+13.3.29 reboot
+--------------
+
+ -- Command: reboot
+ Reboot the computer.
+
+13.3.30 read
+------------
+
+ -- Command: read addr
+ Read a 32-bit value from memory at address ADDR and display it in
+ hex format.
+
+13.3.31 root
+------------
+
+ -- Command: root device [hdbias]
+ Set the current "root device" to the device DEVICE, then attempt
+ to mount it to get the partition size (for passing the partition
+ descriptor in `ES:ESI', used by some chain-loaded boot loaders),
+ the BSD drive-type (for booting BSD kernels using their native
+ boot format), and correctly determine the PC partition where a BSD
+ sub-partition is located. The optional HDBIAS parameter is a
+ number to tell a BSD kernel how many BIOS drive numbers are on
+ controllers before the current one. For example, if there is an
+ IDE disk and a SCSI disk, and your FreeBSD root partition is on
+ the SCSI disk, then use a `1' for HDBIAS.
+
+ See also *Note rootnoverify::.
+
+13.3.32 rootnoverify
+--------------------
+
+ -- Command: rootnoverify device [hdbias]
+ Similar to `root' (*note root::), but don't attempt to mount the
+ partition. This is useful for when an OS is outside of the area of
+ the disk that GRUB can read, but setting the correct root device
+ is still desired. Note that the items mentioned in `root' above
+ which derived from attempting the mount will _not_ work correctly.
+
+13.3.33 savedefault
+-------------------
+
+ -- Command: savedefault num
+ Save the current menu entry or NUM if specified as a default
+ entry. Here is an example:
+
+ default saved
+ timeout 10
+
+ title GNU/Linux
+ root (hd0,0)
+ kernel /boot/vmlinuz root=/dev/sda1 vga=ext
+ initrd /boot/initrd
+ savedefault
+
+ title FreeBSD
+ root (hd0,a)
+ kernel /boot/loader
+ savedefault
+
+ With this configuration, GRUB will choose the entry booted
+ previously as the default entry.
+
+ You can specify `fallback' instead of a number. Then, next
+ fallback entry is saved. Next fallback entry is chosen from
+ fallback entries. Normally, this will be the first entry in
+ fallback ones.
+
+ See also *Note default:: and *Note Invoking grub-set-default::.
+
+13.3.34 setup
+-------------
+
+ -- Command: setup [`--force-lba'] [`--stage2=os_stage2_file']
+ [`--prefix=dir'] install_device [image_device]
+ Set up the installation of GRUB automatically. This command uses
+ the more flexible command `install' (*note install::) in the
+ backend and installs GRUB into the device INSTALL_DEVICE. If
+ IMAGE_DEVICE is specified, then find the GRUB images (*note
+ Images::) in the device IMAGE_DEVICE, otherwise use the current
+ "root device", which can be set by the command `root'. If
+ INSTALL_DEVICE is a hard disk, then embed a Stage 1.5 in the disk
+ if possible.
+
+ The option `--prefix' specifies the directory under which GRUB
+ images are put. If it is not specified, GRUB automatically
+ searches them in `/boot/grub' and `/grub'.
+
+ The options `--force-lba' and `--stage2' are just passed to
+ `install' if specified. *Note install::, for more information.
+
+13.3.35 testload
+----------------
+
+ -- Command: testload file
+ Read the entire contents of FILE in several different ways and
+ compare them, to test the filesystem code. The output is somewhat
+ cryptic, but if no errors are reported and the final `i=X,
+ filepos=Y' reading has X and Y equal, then it is definitely
+ consistent, and very likely works correctly subject to a
+ consistent offset error. If this test succeeds, then a good next
+ step is to try loading a kernel.
+
+13.3.36 testvbe
+---------------
+
+ -- Command: testvbe mode
+ Test the VESA BIOS EXTENSION mode MODE. This command will switch
+ your video card to the graphics mode, and show an endless
+ animation. Hit any key to return. See also *Note vbeprobe::.
+
+13.3.37 uppermem
+----------------
+
+ -- Command: uppermem kbytes
+ Force GRUB to assume that only KBYTES kilobytes of upper memory
+ are installed. Any system address range maps are discarded.
+
+ *Caution:* This should be used with great caution, and should only
+ be necessary on some old machines. GRUB's BIOS probe can pick up
+ all RAM on all new machines the author has ever heard of. It can
+ also be used for debugging purposes to lie to an OS.
+
+13.3.38 vbeprobe
+----------------
+
+ -- Command: vbeprobe [mode]
+ Probe VESA BIOS EXTENSION information. If the mode MODE is
+ specified, show only the information about MODE. Otherwise, this
+ command lists up available VBE modes on the screen. See also *Note
+ testvbe::.
+
+14 Error messages reported by GRUB
+**********************************
+
+This chapter describes error messages reported by GRUB when you
+encounter trouble. *Note Invoking the grub shell::, if your problem is
+specific to the grub shell.
+
+14.1 Errors reported by the Stage 1
+===================================
+
+The general way that the Stage 1 handles errors is to print an error
+string and then halt. Pressing `<CTRL>-<ALT>-<DEL>' will reboot.
+
+ The following is a comprehensive list of error messages for the
+Stage 1:
+
+Hard Disk Error
+ The stage2 or stage1.5 is being read from a hard disk, and the
+ attempt to determine the size and geometry of the hard disk failed.
+
+Floppy Error
+ The stage2 or stage1.5 is being read from a floppy disk, and the
+ attempt to determine the size and geometry of the floppy disk
+ failed. It's listed as a separate error since the probe sequence
+ is different than for hard disks.
+
+Read Error
+ A disk read error happened while trying to read the stage2 or
+ stage1.5.
+
+Geom Error
+ The location of the stage2 or stage1.5 is not in the portion of
+ the disk supported directly by the BIOS read calls. This could
+ occur because the BIOS translated geometry has been changed by the
+ user or the disk is moved to another machine or controller after
+ installation, or GRUB was not installed using itself (if it was,
+ the Stage 2 version of this error would have been seen during that
+ process and it would not have completed the install).
+
+14.2 Errors reported by the Stage 1.5
+=====================================
+
+The general way that the Stage 1.5 handles errors is to print an error
+number in the form `Error NUM' and then halt. Pressing
+`<CTRL>-<ALT>-<DEL>' will reboot.
+
+ The error numbers correspond to the errors reported by Stage 2.
+*Note Stage2 errors::.
+
+14.3 Errors reported by the Stage 2
+===================================
+
+The general way that the Stage 2 handles errors is to abort the
+operation in question, print an error string, then (if possible) either
+continue based on the fact that an error occurred or wait for the user
+to deal with the error.
+
+ The following is a comprehensive list of error messages for the
+Stage 2 (error numbers for the Stage 1.5 are listed before the colon in
+each description):
+
+1 : Filename must be either an absolute filename or blocklist
+ This error is returned if a file name is requested which doesn't
+ fit the syntax/rules listed in the *Note Filesystem::.
+
+2 : Bad file or directory type
+ This error is returned if a file requested is not a regular file,
+ but something like a symbolic link, directory, or FIFO.
+
+3 : Bad or corrupt data while decompressing file
+ This error is returned if the run-length decompression code gets an
+ internal error. This is usually from a corrupt file.
+
+4 : Bad or incompatible header in compressed file
+ This error is returned if the file header for a supposedly
+ compressed file is bad.
+
+5 : Partition table invalid or corrupt
+ This error is returned if the sanity checks on the integrity of the
+ partition table fail. This is a bad sign.
+
+6 : Mismatched or corrupt version of stage1/stage2
+ This error is returned if the install command points to
+ incompatible or corrupt versions of the stage1 or stage2. It can't
+ detect corruption in general, but this is a sanity check on the
+ version numbers, which should be correct.
+
+7 : Loading below 1MB is not supported
+ This error is returned if the lowest address in a kernel is below
+ the 1MB boundary. The Linux zImage format is a special case and
+ can be handled since it has a fixed loading address and maximum
+ size.
+
+8 : Kernel must be loaded before booting
+ This error is returned if GRUB is told to execute the boot sequence
+ without having a kernel to start.
+
+9 : Unknown boot failure
+ This error is returned if the boot attempt did not succeed for
+ reasons which are unknown.
+
+10 : Unsupported Multiboot features requested
+ This error is returned when the Multiboot features word in the
+ Multiboot header requires a feature that is not recognized. The
+ point of this is that the kernel requires special handling which
+ GRUB is probably unable to provide.
+
+11 : Unrecognized device string
+ This error is returned if a device string was expected, and the
+ string encountered didn't fit the syntax/rules listed in the *Note
+ Filesystem::.
+
+12 : Invalid device requested
+ This error is returned if a device string is recognizable but does
+ not fall under the other device errors.
+
+13 : Invalid or unsupported executable format
+ This error is returned if the kernel image being loaded is not
+ recognized as Multiboot or one of the supported native formats
+ (Linux zImage or bzImage, FreeBSD, or NetBSD).
+
+14 : Filesystem compatibility error, cannot read whole file
+ Some of the filesystem reading code in GRUB has limits on the
+ length of the files it can read. This error is returned when the
+ user runs into such a limit.
+
+15 : File not found
+ This error is returned if the specified file name cannot be found,
+ but everything else (like the disk/partition info) is OK.
+
+16 : Inconsistent filesystem structure
+ This error is returned by the filesystem code to denote an internal
+ error caused by the sanity checks of the filesystem structure on
+ disk not matching what it expects. This is usually caused by a
+ corrupt filesystem or bugs in the code handling it in GRUB.
+
+17 : Cannot mount selected partition
+ This error is returned if the partition requested exists, but the
+ filesystem type cannot be recognized by GRUB.
+
+18 : Selected cylinder exceeds maximum supported by BIOS
+ This error is returned when a read is attempted at a linear block
+ address beyond the end of the BIOS translated area. This generally
+ happens if your disk is larger than the BIOS can handle (512MB for
+ (E)IDE disks on older machines or larger than 8GB in general).
+
+19 : Linux kernel must be loaded before initrd
+ This error is returned if the initrd command is used before
+ loading a Linux kernel.
+
+20 : Multiboot kernel must be loaded before modules
+ This error is returned if the module load command is used before
+ loading a Multiboot kernel. It only makes sense in this case
+ anyway, as GRUB has no idea how to communicate the presence of
+ such modules to a non-Multiboot-aware kernel.
+
+21 : Selected disk does not exist
+ This error is returned if the device part of a device- or full
+ file name refers to a disk or BIOS device that is not present or
+ not recognized by the BIOS in the system.
+
+22 : No such partition
+ This error is returned if a partition is requested in the device
+ part of a device- or full file name which isn't on the selected
+ disk.
+
+23 : Error while parsing number
+ This error is returned if GRUB was expecting to read a number and
+ encountered bad data.
+
+24 : Attempt to access block outside partition
+ This error is returned if a linear block address is outside of the
+ disk partition. This generally happens because of a corrupt
+ filesystem on the disk or a bug in the code handling it in GRUB
+ (it's a great debugging tool).
+
+25 : Disk read error
+ This error is returned if there is a disk read error when trying to
+ probe or read data from a particular disk.
+
+26 : Too many symbolic links
+ This error is returned if the link count is beyond the maximum
+ (currently 5), possibly the symbolic links are looped.
+
+27 : Unrecognized command
+ This error is returned if an unrecognized command is entered on the
+ command-line or in a boot sequence section of a configuration file
+ and that entry is selected.
+
+28 : Selected item cannot fit into memory
+ This error is returned if a kernel, module, or raw file load
+ command is either trying to load its data such that it won't fit
+ into memory or it is simply too big.
+
+29 : Disk write error
+ This error is returned if there is a disk write error when trying
+ to write to a particular disk. This would generally only occur
+ during an install of set active partition command.
+
+30 : Invalid argument
+ This error is returned if an argument specified to a command is
+ invalid.
+
+31 : File is not sector aligned
+ This error may occur only when you access a ReiserFS partition by
+ block-lists (e.g. the command `install'). In this case, you should
+ mount the partition with the `-o notail' option.
+
+32 : Must be authenticated
+ This error is returned if you try to run a locked entry. You should
+ enter a correct password before running such an entry.
+
+33 : Serial device not configured
+ This error is returned if you try to change your terminal to a
+ serial one before initializing any serial device.
+
+34 : No spare sectors on the disk
+ This error is returned if a disk doesn't have enough spare space.
+ This happens when you try to embed Stage 1.5 into the unused
+ sectors after the MBR, but the first partition starts right after
+ the MBR or they are used by EZ-BIOS.
+
+15 Invoking the grub shell
+**************************
+
+This chapter documents the grub shell `grub'. Note that the grub shell
+is an emulator; it doesn't run under the native environment, so it
+sometimes does something wrong. Therefore, you shouldn't trust it too
+much. If there is anything wrong with it, don't hesitate to try the
+native GRUB environment, especially when it guesses a wrong map between
+BIOS drives and OS devices.
+
+15.1 Introduction into the grub shell
+=====================================
+
+You can use the command `grub' for installing GRUB under your operating
+systems and for a testbed when you add a new feature into GRUB or when
+fixing a bug. `grub' is almost the same as the Stage 2, and, in fact,
+it shares the source code with the Stage 2 and you can use the same
+commands (*note Commands::) in `grub'. It is emulated by replacing BIOS
+calls with UNIX system calls and libc functions.
+
+ The command `grub' accepts the following options:
+
+`--help'
+ Print a summary of the command-line options and exit.
+
+`--version'
+ Print the version number of GRUB and exit.
+
+`--verbose'
+ Print some verbose messages for debugging purpose.
+
+`--device-map=FILE'
+ Use the device map file FILE. The format is described in *Note
+ Device map::.
+
+`--no-floppy'
+ Do not probe any floppy drive. This option has no effect if the
+ option `--device-map' is specified (*note Device map::).
+
+`--probe-second-floppy'
+ Probe the second floppy drive. If this option is not specified,
+ the grub shell does not probe it, as that sometimes takes a long
+ time. If you specify the device map file (*note Device map::), the
+ grub shell just ignores this option.
+
+`--config-file=FILE'
+ Read the configuration file FILE instead of `/boot/grub/menu.lst'.
+ The format is the same as the normal GRUB syntax. See *Note
+ Filesystem::, for more information.
+
+`--boot-drive=DRIVE'
+ Set the stage2 BOOT_DRIVE to DRIVE. This argument should be an
+ integer (decimal, octal or hexadecimal).
+
+`--install-partition=PAR'
+ Set the stage2 INSTALL_PARTITION to PAR. This argument should be
+ an integer (decimal, octal or hexadecimal).
+
+`--no-config-file'
+ Do not use the configuration file even if it can be read.
+
+`--no-curses'
+ Do not use the screen handling interface by the curses even if it
+ is available.
+
+`--batch'
+ This option has the same meaning as `--no-config-file --no-curses'.
+
+`--read-only'
+ Disable writing to any disk.
+
+`--hold'
+ Wait until a debugger will attach. This option is useful when you
+ want to debug the startup code.
+
+15.2 How to install GRUB via `grub'
+===================================
+
+The installation procedure is the same as under the "native" Stage 2.
+*Note Installation::, for more information. The command `grub'-specific
+information is described here.
+
+ What you should be careful about is "buffer cache". `grub' makes use
+of raw devices instead of filesystems that your operating systems
+serve, so there exists a potential problem that some cache
+inconsistency may corrupt your filesystems. What we recommend is:
+
+ * If you can unmount drives to which GRUB may write any amount of
+ data, unmount them before running `grub'.
+
+ * If a drive cannot be unmounted but can be mounted with the
+ read-only flag, mount it in read-only mode. That should be secure.
+
+ * If a drive must be mounted with the read-write flag, make sure
+ that no activity is being done on it while the command `grub' is
+ running.
+
+ * Reboot your operating system as soon as possible. This is probably
+ not required if you follow the rules above, but reboot is the most
+ secure way.
+
+ In addition, enter the command `quit' when you finish the
+installation. That is _very important_ because `quit' makes the buffer
+cache consistent. Do not push <C-c>.
+
+ If you want to install GRUB non-interactively, specify `--batch'
+option in the command-line. This is a simple example:
+
+ #!/bin/sh
+
+ # Use /usr/sbin/grub if you are on an older system.
+ /sbin/grub --batch <<EOT 1>/dev/null 2>/dev/null
+ root (hd0,0)
+ setup (hd0)
+ quit
+ EOT
+
+15.3 The map between BIOS drives and OS devices
+===============================================
+
+When you specify the option `--device-map' (*note Basic usage::), the
+grub shell creates the "device map file" automatically unless it
+already exists. The file name `/boot/grub/device.map' is preferred.
+
+ If the device map file exists, the grub shell reads it to map BIOS
+drives to OS devices. This file consists of lines like this:
+
+ DEVICE FILE
+
+ DEVICE is a drive specified in the GRUB syntax (*note Device
+syntax::), and FILE is an OS file, which is normally a device file.
+
+ The reason why the grub shell gives you the device map file is that
+it cannot guess the map between BIOS drives and OS devices correctly in
+some environments. For example, if you exchange the boot sequence
+between IDE and SCSI in your BIOS, it gets the order wrong.
+
+ Thus, edit the file if the grub shell makes a mistake. You can put
+any comments in the file if needed, as the grub shell assumes that a
+line is just a comment if the first character is `#'.
+
+16 Invoking grub-install
+************************
+
+The program `grub-install' installs GRUB on your drive using the grub
+shell (*note Invoking the grub shell::). You must specify the device
+name on which you want to install GRUB, like this:
+
+ grub-install INSTALL_DEVICE
+
+ The device name INSTALL_DEVICE is an OS device name or a GRUB device
+name.
+
+ `grub-install' accepts the following options:
+
+`--help'
+ Print a summary of the command-line options and exit.
+
+`--version'
+ Print the version number of GRUB and exit.
+
+`--force-lba'
+ Force GRUB to use LBA mode even for a buggy BIOS. Use this option
+ only if your BIOS doesn't work properly in LBA mode even though it
+ supports LBA mode.
+
+`--root-directory=DIR'
+ Install GRUB images under the directory DIR instead of the root
+ directory. This option is useful when you want to install GRUB
+ into a separate partition or a removable disk. Here is an example
+ in which you have a separate "boot" partition which is mounted on
+ `/boot':
+
+ grub-install --root-directory=/boot hd0
+
+`--grub-shell=FILE'
+ Use FILE as the grub shell. You can append arbitrary options to
+ FILE after the file name, like this:
+
+ grub-install --grub-shell="grub --read-only" /dev/fd0
+
+`--recheck'
+ Recheck the device map, even if `/boot/grub/device.map' already
+ exists. You should use this option whenever you add/remove a disk
+ into/from your computer.
+
+17 Invoking grub-md5-crypt
+**************************
+
+The program `grub-md5-crypt' encrypts a password in MD5 format. This
+is just a frontend of the grub shell (*note Invoking the grub shell::).
+Passwords encrypted by this program can be used with the command
+`password' (*note password::).
+
+ `grub-md5-crypt' accepts the following options:
+
+`--help'
+ Print a summary of the command-line options and exit.
+
+`--version'
+ Print the version information and exit.
+
+`--grub-shell=FILE'
+ Use FILE as the grub shell.
+
+18 Invoking grub-terminfo
+*************************
+
+The program `grub-terminfo' generates a terminfo command from a
+terminfo name (*note terminfo::). The result can be used in the
+configuration file, to define escape sequences. Because GRUB assumes
+that your terminal is vt100-compatible by default, this would be useful
+only if your terminal is uncommon (such as vt52).
+
+ `grub-terminfo' accepts the following options:
+
+`--help'
+ Print a summary of the command-line options and exit.
+
+`--version'
+ Print the version information and exit.
+
+ You must specify one argument to this command. For example:
+
+ grub-terminfo vt52
+
+19 Invoking grub-set-default
+****************************
+
+The program `grub-set-default' sets the default boot entry for GRUB.
+This automatically creates a file named `default' under your GRUB
+directory (i.e. `/boot/grub'), if it is not present. This file is used
+to determine the default boot entry when GRUB boots up your system when
+you use `default saved' in your configuration file (*note default::),
+and to save next default boot entry when you use `savedefault' in a
+boot entry (*note savedefault::).
+
+ `grub-set-default' accepts the following options:
+
+`--help'
+ Print a summary of the command-line options and exit.
+
+`--version'
+ Print the version information and exit.
+
+`--root-directory=DIR'
+ Use the directory DIR instead of the root directory (i.e. `/') to
+ define the location of the default file. This is useful when you
+ mount a disk which is used for another system.
+
+ You must specify a single argument to `grub-set-default'. This
+argument is normally the number of a default boot entry. For example,
+if you have this configuration file:
+
+ default saved
+ timeout 10
+
+ title GNU/Hurd
+ root (hd0,0)
+ ...
+
+ title GNU/Linux
+ root (hd0,1)
+ ...
+
+ and if you want to set the next default boot entry to GNU/Linux, you
+may execute this command:
+
+ grub-set-default 1
+
+ Because the entry for GNU/Linux is `1'. Note that entries are
+counted from zero. So, if you want to specify GNU/Hurd here, then you
+should specify `0'.
+
+ This feature is very useful if you want to test a new kernel or to
+make your system quite robust. *Note Making your system robust::, for
+more hints about how to set up a robust system.
+
+20 Invoking mbchk
+*****************
+
+The program `mbchk' checks for the format of a Multiboot kernel. We
+recommend using this program before booting your own kernel by GRUB.
+
+ `mbchk' accepts the following options:
+
+`--help'
+ Print a summary of the command-line options and exit.
+
+`--version'
+ Print the version number of GRUB and exit.
+
+`--quiet'
+ Suppress all normal output.
+
+Appendix A How to obtain and build GRUB
+***************************************
+
+ *Caution:* GRUB requires binutils-2.9.1.0.23 or later because the
+ GNU assembler has been changed so that it can produce real 16bits
+ machine code between 2.9.1 and 2.9.1.0.x. See
+ `http://sources.redhat.com/binutils/', to obtain information on
+ how to get the latest version.
+
+ GRUB is available from the GNU alpha archive site
+`ftp://alpha.gnu.org/gnu/grub' or any of its mirrors. The file will be
+named grub-version.tar.gz. The current version is 0.97, so the file you
+should grab is:
+
+ `ftp://alpha.gnu.org/gnu/grub/grub-0.97.tar.gz'
+
+ To unbundle GRUB use the instruction:
+
+ zcat grub-0.97.tar.gz | tar xvf -
+
+ which will create a directory called `grub-0.97' with all the
+sources. You can look at the file `INSTALL' for detailed instructions
+on how to build and install GRUB, but you should be able to just do:
+
+ cd grub-0.97
+ ./configure
+ make install
+
+ This will install the grub shell `grub' (*note Invoking the grub
+shell::), the Multiboot checker `mbchk' (*note Invoking mbchk::), and
+the GRUB images. This will also install the GRUB manual.
+
+ Also, the latest version is available from the CVS. See
+`http://savannah.gnu.org/cvs/?group=grub' for more information.
+
+Appendix B Reporting bugs
+*************************
+
+These are the guideline for how to report bugs. Take a look at this
+list below before you submit bugs:
+
+ 1. Before getting unsettled, read this manual through and through.
+ Also, see the GNU GRUB FAQ
+ (http://www.gnu.org/software/grub/grub-faq.html).
+
+ 2. Always mention the information on your GRUB. The version number
+ and the configuration are quite important. If you build it
+ yourself, write the options specified to the configure script and
+ your operating system, including the versions of gcc and binutils.
+
+ 3. If you have trouble with the installation, inform us of how you
+ installed GRUB. Don't omit error messages, if any. Just `GRUB hangs
+ up when it boots' is not enough.
+
+ The information on your hardware is also essential. These are
+ especially important: the geometries and the partition tables of
+ your hard disk drives and your BIOS.
+
+ 4. If GRUB cannot boot your operating system, write down _everything_
+ you see on the screen. Don't paraphrase them, like `The foo OS
+ crashes with GRUB, even though it can boot with the bar boot
+ loader just fine'. Mention the commands you executed, the messages
+ printed by them, and information on your operating system
+ including the version number.
+
+ 5. Explain what you wanted to do. It is very useful to know your
+ purpose and your wish, and how GRUB didn't satisfy you.
+
+ 6. If you can investigate the problem yourself, please do. That will
+ give you and us much more information on the problem. Attaching a
+ patch is even better.
+
+ When you attach a patch, make the patch in unified diff format, and
+ write ChangeLog entries. But, even when you make a patch, don't
+ forget to explain the problem, so that we can understand what your
+ patch is for.
+
+ 7. Write down anything that you think might be related. Please
+ understand that we often need to reproduce the same problem you
+ encounterred in our environment. So your information should be
+ sufficient for us to do the same thing--Don't forget that we
+ cannot see your computer directly. If you are not sure whether to
+ state a fact or leave it out, state it! Reporting too many things
+ is much better than omitting something important.
+
+ If you follow the guideline above, submit a report to the Bug
+Tracking System (http://savannah.gnu.org/bugs/?group=grub).
+Alternatively, you can submit a report via electronic mail to
+<bug-grub@gnu.org>, but we strongly recommend that you use the Bug
+Tracking System, because e-mail can be passed over easily.
+
+ Once we get your report, we will try to fix the bugs.
+
+Appendix C Where GRUB will go
+*****************************
+
+We started the next generation of GRUB, GRUB 2. This will include
+internationalization, dynamic module loading, real memory management,
+multiple architecture support, a scripting language, and many other
+nice feature. If you are interested in the development of GRUB 2, take
+a look at the homepage (http://www.gnu.org/software/grub/grub.html).
+
+Appendix D Hacking GRUB
+***********************
+
+This chapter documents the user-invisible aspect of GRUB.
+
+ As a general rule of software development, it is impossible to keep
+the descriptions of the internals up-to-date, and it is quite hard to
+document everything. So refer to the source code, whenever you are not
+satisfied with this documentation. Please assume that this gives just
+hints to you.
+
+D.1 The memory map of various components
+========================================
+
+GRUB consists of two distinct components, called "stages", which are
+loaded at different times in the boot process. Because they run
+mutual-exclusively, sometimes a memory area overlaps with another
+memory area. And, even in one stage, a single memory area can be used
+for various purposes, because their usages are mutually exclusive.
+
+ Here is the memory map of the various components:
+
+0 to 4K-1
+ BIOS and real mode interrupts
+
+0x07BE to 0x07FF
+ Partition table passed to another boot loader
+
+down from 8K-1
+ Real mode stack
+
+0x2000 to ?
+ The optional Stage 1.5 is loaded here
+
+0x2000 to 0x7FFF
+ Command-line buffer for Multiboot kernels and modules
+
+0x7C00 to 0x7DFF
+ Stage 1 is loaded here by BIOS or another boot loader
+
+0x7F00 to 0x7F42
+ LBA drive parameters
+
+0x8000 to ?
+ Stage2 is loaded here
+
+The end of Stage 2 to 416K-1
+ Heap, in particular used for the menu
+
+down from 416K-1
+ Protected mode stack
+
+416K to 448K-1
+ Filesystem buffer
+
+448K to 479.5K-1
+ Raw device buffer
+
+479.5K to 480K-1
+ 512-byte scratch area
+
+480K to 512K-1
+ Buffers for various functions, such as password, command-line, cut
+ and paste, and completion.
+
+The last 1K of lower memory
+ Disk swapping code and data
+
+ See the file `stage2/shared.h', for more information.
+
+D.2 Embedded variables in GRUB
+==============================
+
+Stage 1 and Stage 2 have embedded variables whose locations are
+well-defined, so that the installation can patch the binary file
+directly without recompilation of the stages.
+
+ In Stage 1, these are defined:
+
+`0x3E'
+ The version number (not GRUB's, but the installation mechanism's).
+
+`0x40'
+ The boot drive. If it is 0xFF, use a drive passed by BIOS.
+
+`0x41'
+ The flag for if forcing LBA.
+
+`0x42'
+ The starting address of Stage 2.
+
+`0x44'
+ The first sector of Stage 2.
+
+`0x48'
+ The starting segment of Stage 2.
+
+`0x1FE'
+ The signature (`0xAA55').
+
+ See the file `stage1/stage1.S', for more information.
+
+ In the first sector of Stage 1.5 and Stage 2, the block lists are
+recorded between `firstlist' and `lastlist'. The address of `lastlist'
+is determined when assembling the file `stage2/start.S'.
+
+ The trick here is that it is actually read backward, and the first
+8-byte block list is not read here, but after the pointer is decremented
+8 bytes, then after reading it, it decrements again, reads, and so on,
+until it is finished. The terminating condition is when the number of
+sectors to be read in the next block list is zero.
+
+ The format of a block list can be seen from the example in the code
+just before the `firstlist' label. Note that it is always from the
+beginning of the disk, but _not_ relative to the partition boundaries.
+
+ In the second sector of Stage 1.5 and Stage 2, these are defined:
+
+`0x6'
+ The version number (likewise, the installation mechanism's).
+
+`0x8'
+ The installed partition.
+
+`0xC'
+ The saved entry number.
+
+`0x10'
+ The identifier.
+
+`0x11'
+ The flag for if forcing LBA.
+
+`0x12'
+ The version string (GRUB's).
+
+`0x12' + "the length of the version string"
+ The name of a configuration file.
+
+ See the file `stage2/asm.S', for more information.
+
+D.3 The generic interface for filesystems
+=========================================
+
+For any particular partition, it is presumed that only one of the
+"normal" filesystems such as FAT, FFS, or ext2fs can be used, so there
+is a switch table managed by the functions in `disk_io.c'. The notation
+is that you can only "mount" one at a time.
+
+ The block list filesystem has a special place in the system. In
+addition to the "normal" filesystem (or even without one mounted), you
+can access disk blocks directly (in the indicated partition) via the
+block list notation. Using the block list filesystem doesn't effect any
+other filesystem mounts.
+
+ The variables which can be read by the filesystem backend are:
+
+`current_drive'
+ The current BIOS drive number (numbered from 0, if a floppy, and
+ numbered from 0x80, if a hard disk).
+
+`current_partition'
+ The current partition number.
+
+`current_slice'
+ The current partition type.
+
+`saved_drive'
+ The "drive" part of the root device.
+
+`saved_partition'
+ The "partition" part of the root device.
+
+`part_start'
+ The current partition starting address, in sectors.
+
+`part_length'
+ The current partition length, in sectors.
+
+`print_possibilities'
+ True when the `dir' function should print the possible completions
+ of a file, and false when it should try to actually open a file of
+ that name.
+
+`FSYS_BUF'
+ Filesystem buffer which is 32K in size, to use in any way which the
+ filesystem backend desires.
+
+ The variables which need to be written by a filesystem backend are:
+
+`filepos'
+ The current position in the file, in sectors.
+
+ *Caution:* the value of FILEPOS can be changed out from under the
+ filesystem code in the current implementation. Don't depend on it
+ being the same for later calls into the backend code!
+
+`filemax'
+ The length of the file.
+
+`disk_read_func'
+ The value of DISK_READ_HOOK _only_ during reading of data for the
+ file, not any other fs data, inodes, FAT tables, whatever, then
+ set to `NULL' at all other times (it will be `NULL' by default).
+ If this isn't done correctly, then the `testload' and `install'
+ commands won't work correctly.
+
+ The functions expected to be used by the filesystem backend are:
+
+`devread'
+ Only read sectors from within a partition. Sector 0 is the first
+ sector in the partition.
+
+`grub_read'
+ If the backend uses the block list code, then `grub_read' can be
+ used, after setting BLOCK_FILE to 1.
+
+`print_a_completion'
+ If PRINT_POSSIBILITIES is true, call `print_a_completion' for each
+ possible file name. Otherwise, the file name completion won't work.
+
+ The functions expected to be defined by the filesystem backend are
+described at least moderately in the file `filesys.h'. Their usage is
+fairly evident from their use in the functions in `disk_io.c', look for
+the use of the FSYS_TABLE array.
+
+ *Caution:* The semantics are such that then `mount'ing the
+filesystem, presume the filesystem buffer `FSYS_BUF' is corrupted, and
+(re-)load all important contents. When opening and reading a file,
+presume that the data from the `mount' is available, and doesn't get
+corrupted by the open/read (i.e. multiple opens and/or reads will be
+done with only one mount if in the same filesystem).
+
+D.4 The generic interface for built-ins
+=======================================
+
+GRUB built-in commands are defined in a uniformal interface, whether
+they are menu-specific or can be used anywhere. The definition of a
+builtin command consists of two parts: the code itself and the table of
+the information.
+
+ The code must be a function which takes two arguments, a command-line
+string and flags, and returns an `int' value. The "flags" argument
+specifies how the function is called, using a bit mask. The return
+value must be zero if successful, otherwise non-zero. So it is normally
+enough to return ERRNUM.
+
+ The table of the information is represented by the structure `struct
+builtin', which contains the name of the command, a pointer to the
+function, flags, a short description of the command and a long
+description of the command. Since the descriptions are used only for
+help messages interactively, you don't have to define them, if the
+command may not be called interactively (such as `title').
+
+ The table is finally registered in the table BUILTIN_TABLE, so that
+`run_script' and `enter_cmdline' can find the command. See the files
+`cmdline.c' and `builtins.c', for more details.
+
+D.5 The bootstrap mechanism used in GRUB
+========================================
+
+The disk space can be used in a boot loader is very restricted because
+a MBR (*note MBR::) is only 512 bytes but it also contains a partition
+table (*note Partition table::) and a BPB. So the question is how to
+make a boot loader code enough small to be fit in a MBR.
+
+ However, GRUB is a very large program, so we break GRUB into 2 (or 3)
+distinct components, "Stage 1" and "Stage 2" (and optionally "Stage
+1.5"). *Note Memory map::, for more information.
+
+ We embed Stage 1 in a MBR or in the boot sector of a partition, and
+place Stage 2 in a filesystem. The optional Stage 1.5 can be installed
+in a filesystem, in the "boot loader" area in a FFS or a ReiserFS, and
+in the sectors right after a MBR, because Stage 1.5 is enough small and
+the sectors right after a MBR is normally an unused region. The size of
+this region is the number of sectors per head minus 1.
+
+ Thus, all Stage1 must do is just load Stage2 or Stage1.5. But even if
+Stage 1 needs not to support the user interface or the filesystem
+interface, it is impossible to make Stage 1 less than 400 bytes, because
+GRUB should support both the CHS mode and the LBA mode (*note Low-level
+disk I/O::).
+
+ The solution used by GRUB is that Stage 1 loads only the first
+sector of Stage 2 (or Stage 1.5) and Stage 2 itself loads the rest. The
+flow of Stage 1 is:
+
+ 1. Initialize the system briefly.
+
+ 2. Detect the geometry and the accessing mode of the "loading drive".
+
+ 3. Load the first sector of Stage 2.
+
+ 4. Jump to the starting address of the Stage 2.
+
+ The flow of Stage 2 (and Stage 1.5) is:
+
+ 1. Load the rest of itself to the real starting address, that is, the
+ starting address plus 512 bytes. The block lists are stored in the
+ last part of the first sector.
+
+ 2. Long jump to the real starting address.
+
+ Note that Stage 2 (or Stage 1.5) does not probe the geometry or the
+accessing mode of the "loading drive", since Stage 1 has already probed
+them.
+
+D.6 How to probe I/O ports used by INT 13H
+==========================================
+
+FIXME: I will write this chapter after implementing the new technique.
+
+D.7 How to detect all installed RAM
+===================================
+
+FIXME: I doubt if Erich didn't write this chapter only himself wholly,
+so I will rewrite this chapter.
+
+D.8 INT 13H disk I/O interrupts
+===============================
+
+FIXME: I'm not sure where some part of the original chapter is derived,
+so I will rewrite this chapter.
+
+D.9 The structure of Master Boot Record
+=======================================
+
+FIXME: Likewise.
+
+D.10 The format of partition tables
+===================================
+
+FIXME: Probably the original chapter is derived from "How It Works", so
+I will rewrite this chapter.
+
+D.11 Where and how you should send patches
+==========================================
+
+When you write patches for GRUB, please send them to the mailing list
+<bug-grub@gnu.org>. Here is the list of items of which you should take
+care:
+
+ * Please make your patch as small as possible. Generally, it is not
+ a good thing to make one big patch which changes many things.
+ Instead, segregate features and produce many patches.
+
+ * Use as late code as possible, for the original code. The CVS
+ repository always has the current version (*note Obtaining and
+ Building GRUB::).
+
+ * Write ChangeLog entries. *Note Change Logs: (standards)Change
+ Logs, if you don't know how to write ChangeLog.
+
+ * Make patches in unified diff format. `diff -urN' is appropriate in
+ most cases.
+
+ * Don't make patches reversely. Reverse patches are difficult to
+ read and use.
+
+ * Be careful enough of the license term and the copyright. Because
+ GRUB is under GNU General Public License, you may not steal code
+ from software whose license is incompatible against GPL. And, if
+ you copy code written by others, you must not ignore their
+ copyrights. Feel free to ask GRUB maintainers, whenever you are
+ not sure what you should do.
+
+ * If your patch is too large to send in e-mail, put it at somewhere
+ we can see. Usually, you shouldn't send e-mail over 20K.
+
+Appendix E Copying This Manual
+******************************
+
+E.1 GNU Free Documentation License
+==================================
+
+ Version 1.2, November 2002
+
+ Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
+ 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ 0. PREAMBLE
+
+ The purpose of this License is to make a manual, textbook, or other
+ functional and useful document "free" in the sense of freedom: to
+ assure everyone the effective freedom to copy and redistribute it,
+ with or without modifying it, either commercially or
+ noncommercially. Secondarily, this License preserves for the
+ author and publisher a way to get credit for their work, while not
+ being considered responsible for modifications made by others.
+
+ This License is a kind of "copyleft", which means that derivative
+ works of the document must themselves be free in the same sense.
+ It complements the GNU General Public License, which is a copyleft
+ license designed for free software.
+
+ We have designed this License in order to use it for manuals for
+ free software, because free software needs free documentation: a
+ free program should come with manuals providing the same freedoms
+ that the software does. But this License is not limited to
+ software manuals; it can be used for any textual work, regardless
+ of subject matter or whether it is published as a printed book.
+ We recommend this License principally for works whose purpose is
+ instruction or reference.
+
+ 1. APPLICABILITY AND DEFINITIONS
+
+ This License applies to any manual or other work, in any medium,
+ that contains a notice placed by the copyright holder saying it
+ can be distributed under the terms of this License. Such a notice
+ grants a world-wide, royalty-free license, unlimited in duration,
+ to use that work under the conditions stated herein. The
+ "Document", below, refers to any such manual or work. Any member
+ of the public is a licensee, and is addressed as "you". You
+ accept the license if you copy, modify or distribute the work in a
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+
+ A "Modified Version" of the Document means any work containing the
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+
+ A "Secondary Section" is a named appendix or a front-matter section
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+
+ The "Invariant Sections" are certain Secondary Sections whose
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+ the notice that says that the Document is released under this
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+ The Document may contain zero Invariant Sections. If the Document
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+
+ The "Cover Texts" are certain short passages of text that are
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+ that says that the Document is released under this License. A
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+ be at most 25 words.
+
+ A "Transparent" copy of the Document means a machine-readable copy,
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+ produced by some word processors for output purposes only.
+
+ The "Title Page" means, for a printed book, the title page itself,
+ plus such following pages as are needed to hold, legibly, the
+ material this License requires to appear in the title page. For
+ works in formats which do not have any title page as such, "Title
+ Page" means the text near the most prominent appearance of the
+ work's title, preceding the beginning of the body of the text.
+
+ A section "Entitled XYZ" means a named subunit of the Document
+ whose title either is precisely XYZ or contains XYZ in parentheses
+ following text that translates XYZ in another language. (Here XYZ
+ stands for a specific section name mentioned below, such as
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+ To "Preserve the Title" of such a section when you modify the
+ Document means that it remains a section "Entitled XYZ" according
+ to this definition.
+
+ The Document may include Warranty Disclaimers next to the notice
+ which states that this License applies to the Document. These
+ Warranty Disclaimers are considered to be included by reference in
+ this License, but only as regards disclaiming warranties: any other
+ implication that these Warranty Disclaimers may have is void and
+ has no effect on the meaning of this License.
+
+ 2. VERBATIM COPYING
+
+ You may copy and distribute the Document in any medium, either
+ commercially or noncommercially, provided that this License, the
+ copyright notices, and the license notice saying this License
+ applies to the Document are reproduced in all copies, and that you
+ add no other conditions whatsoever to those of this License. You
+ may not use technical measures to obstruct or control the reading
+ or further copying of the copies you make or distribute. However,
+ you may accept compensation in exchange for copies. If you
+ distribute a large enough number of copies you must also follow
+ the conditions in section 3.
+
+ You may also lend copies, under the same conditions stated above,
+ and you may publicly display copies.
+
+ 3. COPYING IN QUANTITY
+
+ If you publish printed copies (or copies in media that commonly
+ have printed covers) of the Document, numbering more than 100, and
+ the Document's license notice requires Cover Texts, you must
+ enclose the copies in covers that carry, clearly and legibly, all
+ these Cover Texts: Front-Cover Texts on the front cover, and
+ Back-Cover Texts on the back cover. Both covers must also clearly
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+ front cover must present the full title with all words of the
+ title equally prominent and visible. You may add other material
+ on the covers in addition. Copying with changes limited to the
+ covers, as long as they preserve the title of the Document and
+ satisfy these conditions, can be treated as verbatim copying in
+ other respects.
+
+ If the required texts for either cover are too voluminous to fit
+ legibly, you should put the first ones listed (as many as fit
+ reasonably) on the actual cover, and continue the rest onto
+ adjacent pages.
+
+ If you publish or distribute Opaque copies of the Document
+ numbering more than 100, you must either include a
+ machine-readable Transparent copy along with each Opaque copy, or
+ state in or with each Opaque copy a computer-network location from
+ which the general network-using public has access to download
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+
+ It is requested, but not required, that you contact the authors of
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+
+ 4. MODIFICATIONS
+
+ You may copy and distribute a Modified Version of the Document
+ under the conditions of sections 2 and 3 above, provided that you
+ release the Modified Version under precisely this License, with
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+ licensing distribution and modification of the Modified Version to
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+
+ A. Use in the Title Page (and on the covers, if any) a title
+ distinct from that of the Document, and from those of
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+
+ B. List on the Title Page, as authors, one or more persons or
+ entities responsible for authorship of the modifications in
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+ principal authors of the Document (all of its principal
+ authors, if it has fewer than five), unless they release you
+ from this requirement.
+
+ C. State on the Title page the name of the publisher of the
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+
+ D. Preserve all the copyright notices of the Document.
+
+ E. Add an appropriate copyright notice for your modifications
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+
+ F. Include, immediately after the copyright notices, a license
+ notice giving the public permission to use the Modified
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+ the Addendum below.
+
+ G. Preserve in that license notice the full lists of Invariant
+ Sections and required Cover Texts given in the Document's
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+
+ H. Include an unaltered copy of this License.
+
+ I. Preserve the section Entitled "History", Preserve its Title,
+ and add to it an item stating at least the title, year, new
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+ the Document, create one stating the title, year, authors,
+ and publisher of the Document as given on its Title Page,
+ then add an item describing the Modified Version as stated in
+ the previous sentence.
+
+ J. Preserve the network location, if any, given in the Document
+ for public access to a Transparent copy of the Document, and
+ likewise the network locations given in the Document for
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+ the "History" section. You may omit a network location for a
+ work that was published at least four years before the
+ Document itself, or if the original publisher of the version
+ it refers to gives permission.
+
+ K. For any section Entitled "Acknowledgements" or "Dedications",
+ Preserve the Title of the section, and preserve in the
+ section all the substance and tone of each of the contributor
+ acknowledgements and/or dedications given therein.
+
+ L. Preserve all the Invariant Sections of the Document,
+ unaltered in their text and in their titles. Section numbers
+ or the equivalent are not considered part of the section
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+
+ M. Delete any section Entitled "Endorsements". Such a section
+ may not be included in the Modified Version.
+
+ N. Do not retitle any existing section to be Entitled
+ "Endorsements" or to conflict in title with any Invariant
+ Section.
+
+ O. Preserve any Warranty Disclaimers.
+
+ If the Modified Version includes new front-matter sections or
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+ You may add a section Entitled "Endorsements", provided it contains
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+
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+ passage of Front-Cover Text and one of Back-Cover Text may be
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+ Document already includes a cover text for the same cover,
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+ replace the old one, on explicit permission from the previous
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+
+ The author(s) and publisher(s) of the Document do not by this
+ License give permission to use their names for publicity for or to
+ assert or imply endorsement of any Modified Version.
+
+ 5. COMBINING DOCUMENTS
+
+ You may combine the Document with other documents released under
+ this License, under the terms defined in section 4 above for
+ modified versions, provided that you include in the combination
+ all of the Invariant Sections of all of the original documents,
+ unmodified, and list them all as Invariant Sections of your
+ combined work in its license notice, and that you preserve all
+ their Warranty Disclaimers.
+
+ The combined work need only contain one copy of this License, and
+ multiple identical Invariant Sections may be replaced with a single
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+
+ In the combination, you must combine any sections Entitled
+ "History" in the various original documents, forming one section
+ Entitled "History"; likewise combine any sections Entitled
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+ must delete all sections Entitled "Endorsements."
+
+ 6. COLLECTIONS OF DOCUMENTS
+
+ You may make a collection consisting of the Document and other
+ documents released under this License, and replace the individual
+ copies of this License in the various documents with a single copy
+ that is included in the collection, provided that you follow the
+ rules of this License for verbatim copying of each of the
+ documents in all other respects.
+
+ You may extract a single document from such a collection, and
+ distribute it individually under this License, provided you insert
+ a copy of this License into the extracted document, and follow
+ this License in all other respects regarding verbatim copying of
+ that document.
+
+ 7. AGGREGATION WITH INDEPENDENT WORKS
+
+ A compilation of the Document or its derivatives with other
+ separate and independent documents or works, in or on a volume of
+ a storage or distribution medium, is called an "aggregate" if the
+ copyright resulting from the compilation is not used to limit the
+ legal rights of the compilation's users beyond what the individual
+ works permit. When the Document is included in an aggregate, this
+ License does not apply to the other works in the aggregate which
+ are not themselves derivative works of the Document.
+
+ If the Cover Text requirement of section 3 is applicable to these
+ copies of the Document, then if the Document is less than one half
+ of the entire aggregate, the Document's Cover Texts may be placed
+ on covers that bracket the Document within the aggregate, or the
+ electronic equivalent of covers if the Document is in electronic
+ form. Otherwise they must appear on printed covers that bracket
+ the whole aggregate.
+
+ 8. TRANSLATION
+
+ Translation is considered a kind of modification, so you may
+ distribute translations of the Document under the terms of section
+ 4. Replacing Invariant Sections with translations requires special
+ permission from their copyright holders, but you may include
+ translations of some or all Invariant Sections in addition to the
+ original versions of these Invariant Sections. You may include a
+ translation of this License, and all the license notices in the
+ Document, and any Warranty Disclaimers, provided that you also
+ include the original English version of this License and the
+ original versions of those notices and disclaimers. In case of a
+ disagreement between the translation and the original version of
+ this License or a notice or disclaimer, the original version will
+ prevail.
+
+ If a section in the Document is Entitled "Acknowledgements",
+ "Dedications", or "History", the requirement (section 4) to
+ Preserve its Title (section 1) will typically require changing the
+ actual title.
+
+ 9. TERMINATION
+
+ You may not copy, modify, sublicense, or distribute the Document
+ except as expressly provided for under this License. Any other
+ attempt to copy, modify, sublicense or distribute the Document is
+ void, and will automatically terminate your rights under this
+ License. However, parties who have received copies, or rights,
+ from you under this License will not have their licenses
+ terminated so long as such parties remain in full compliance.
+
+ 10. FUTURE REVISIONS OF THIS LICENSE
+
+ The Free Software Foundation may publish new, revised versions of
+ the GNU Free Documentation License from time to time. Such new
+ versions will be similar in spirit to the present version, but may
+ differ in detail to address new problems or concerns. See
+ `http://www.gnu.org/copyleft/'.
+
+ Each version of the License is given a distinguishing version
+ number. If the Document specifies that a particular numbered
+ version of this License "or any later version" applies to it, you
+ have the option of following the terms and conditions either of
+ that specified version or of any later version that has been
+ published (not as a draft) by the Free Software Foundation. If
+ the Document does not specify a version number of this License,
+ you may choose any version ever published (not as a draft) by the
+ Free Software Foundation.
+
+E.1.1 ADDENDUM: How to use this License for your documents
+----------------------------------------------------------
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and license
+notices just after the title page:
+
+ Copyright (C) YEAR YOUR NAME.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.2
+ or any later version published by the Free Software Foundation;
+ with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
+ Texts. A copy of the license is included in the section entitled ``GNU
+ Free Documentation License''.
+
+ If you have Invariant Sections, Front-Cover Texts and Back-Cover
+Texts, replace the "with...Texts." line with this:
+
+ with the Invariant Sections being LIST THEIR TITLES, with
+ the Front-Cover Texts being LIST, and with the Back-Cover Texts
+ being LIST.
+
+ If you have Invariant Sections without Cover Texts, or some other
+combination of the three, merge those two alternatives to suit the
+situation.
+
+ If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License, to
+permit their use in free software.
+
+Index
+*****
+
+blocklist: See 13.3.1. (line 2252)
+boot: See 13.3.2. (line 2259)
+bootp: See 13.2.1. (line 1862)
+cat: See 13.3.3. (line 2267)
+chainloader: See 13.3.4. (line 2276)
+cmp: See 13.3.5. (line 2288)
+color: See 13.2.2. (line 1874)
+configfile: See 13.3.6. (line 2304)
+current_drive: See D.3. (line 3498)
+current_partition: See D.3. (line 3502)
+current_slice: See D.3. (line 3505)
+debug: See 13.3.7. (line 2310)
+default: See 13.1.1. (line 1810)
+device: See 13.2.3. (line 1935)
+devread: See D.3. (line 3550)
+dhcp: See 13.2.4. (line 1950)
+disk_read_func: See D.3. (line 3541)
+displayapm: See 13.3.8. (line 2319)
+displaymem: See 13.3.9. (line 2325)
+embed: See 13.3.10. (line 2338)
+fallback: See 13.1.2. (line 1822)
+FDL, GNU Free Documentation License: See E.1. (line 3716)
+filemax: See D.3. (line 3538)
+filepos: See D.3. (line 3531)
+find: See 13.3.11. (line 2352)
+fstest: See 13.3.12. (line 2361)
+FSYS_BUF: See D.3. (line 3525)
+geometry: See 13.3.13. (line 2374)
+grub_read: See D.3. (line 3554)
+halt: See 13.3.14. (line 2385)
+help: See 13.3.15. (line 2393)
+hiddenmenu: See 13.1.3. (line 1833)
+hide: See 13.2.5. (line 1963)
+ifconfig: See 13.2.6. (line 1973)
+impsprobe: See 13.3.16. (line 2406)
+initrd: See 13.3.17. (line 2415)
+install: See 13.3.18. (line 2425)
+ioprobe: See 13.3.19. (line 2483)
+kernel: See 13.3.20. (line 2491)
+lock: See 13.3.21. (line 2513)
+makeactive: See 13.3.22. (line 2530)
+map: See 13.3.23. (line 2537)
+md5crypt: See 13.3.24. (line 2551)
+module: See 13.3.25. (line 2559)
+modulenounzip: See 13.3.26. (line 2570)
+pager: See 13.2.7. (line 1983)
+part_length: See D.3. (line 3517)
+part_start: See D.3. (line 3514)
+partnew: See 13.2.8. (line 1991)
+parttype: See 13.2.9. (line 2000)
+password: See 13.2.10. (line 2008)
+pause: See 13.3.27. (line 2577)
+print_a_completion: See D.3. (line 3558)
+print_possibilities: See D.3. (line 3520)
+quit: See 13.3.28. (line 2586)
+rarp: See 13.2.11. (line 2023)
+read: See 13.3.30. (line 2599)
+reboot: See 13.3.29. (line 2593)
+root: See 13.3.31. (line 2606)
+rootnoverify: See 13.3.32. (line 2623)
+saved_drive: See D.3. (line 3508)
+saved_partition: See D.3. (line 3511)
+savedefault: See 13.3.33. (line 2633)
+serial: See 13.2.12. (line 2033)
+setkey: See 13.2.13. (line 2055)
+setup: See 13.3.34. (line 2665)
+terminal: See 13.2.14. (line 2180)
+terminfo: See 13.2.15. (line 2212)
+testload: See 13.3.35. (line 2685)
+testvbe: See 13.3.36. (line 2697)
+tftpserver: See 13.2.16. (line 2225)
+timeout: See 13.1.4. (line 1843)
+title: See 13.1.5. (line 1850)
+unhide: See 13.2.17. (line 2237)
+uppermem: See 13.3.37. (line 2705)
+vbeprobe: See 13.3.38. (line 2717)