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- Committer: Bazaar Package Importer
- Author(s): Colin Watson
- Date: 2010-06-15 12:45:35 UTC
- mto: (1.14.1 upstream) (17.3.18 experimental)
- mto: This revision was merged to the branch mainline in revision 36.
- Revision ID: james.westby@ubuntu.com-20100615124535-9vfbis4kzv0h5bgy
Tags: upstream-1.98+20100614
Import upstream version 1.98+20100614
- files added:
- aclocal.m4
- docs/man
- files removed:
- commands/handler.c
- files modified:
- ChangeLog
added
removed
docs/grub.texi
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* GRUB: (grub). The GRand Unified Bootloader
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* grub-install: (grub)Invoking grub-install. Install GRUB on your drive
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* grub-mkconfig: (grub)Invoking grub-mkconfig. Generate GRUB configuration
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* grub-mkpasswd-pbkdf2: (grub)Invoking grub-mkpasswd-pbkdf2.
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@end direntry
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@setchapternewpage odd
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* Filesystem:: Filesystem syntax and semantics
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* Interface:: The menu and the command-line
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* Commands:: The list of available builtin commands
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* Security:: Authentication and authorisation
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* Troubleshooting:: Error messages produced by GRUB
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* Invoking grub-install:: How to use the GRUB installer
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* Invoking grub-mkconfig:: Generate a GRUB configuration file
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* Invoking grub-mkpasswd-pbkdf2::
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Generate GRUB password hashes
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* Obtaining and Building GRUB:: How to obtain and build GRUB
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* Reporting bugs:: Where you should send a bug report
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* Future:: Some future plans on GRUB
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sources available via anonymous CVS. @xref{Obtaining and Building
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GRUB}, for more information.
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Over the next few years, GRUB was extended to meet many needs, but it
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quickly became clear that its design was not keeping up with the extensions
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being made to it, and we reached the point where it was very difficult to
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make any further changes without breaking existing features. Around 2002,
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Yoshinori K. Okuji started work on PUPA (Preliminary Universal Programming
182
Architecture for GNU GRUB), aiming to rewrite the core of GRUB to make it
183
cleaner, safer, more robust, and more powerful. PUPA was eventually renamed
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to GRUB 2, and the original version of GRUB was renamed to GRUB Legacy.
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Small amounts of maintenance continued to be done on GRUB Legacy, but the
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last release (0.97) was made in 2005 and at the time of writing it seems
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unlikely that there will be another.
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By around 2007, GNU/Linux distributions started to use GRUB 2 to limited
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extents, and by the end of 2009 multiple major distributions were installing
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it by default.
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@node Features
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@section GRUB features
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partition.
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407
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Of course, to actually access the disks or partitions with GRUB, you
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need to use the device specification in a command, like @samp{root
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(fd0)} or @samp{unhide (hd0,3)}. To help you find out which number
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specifies a partition you want, the GRUB command-line
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need to use the device specification in a command, like @samp{set
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root=(fd0)} or @samp{parttool (hd0,3) hidden-}. To help you find out
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which number specifies a partition you want, the GRUB command-line
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(@pxref{Command-line interface}) options have argument
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completion. This means that, for example, you only need to type
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@example
396
root (
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set root=(
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@end example
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followed by a @key{TAB}, and GRUB will display the list of drives,
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@section Writing full configuration files directly
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@node Network
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@chapter Booting GRUB from the network
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The following instructions only work on PC BIOS systems where the Preboot
993
eXecution Environment (PXE) is available.
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To generate a PXE boot image, run:
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@example
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@group
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grub-mkimage --format=i386-pc --output=core.img --prefix='(pxe)/boot/grub' pxe pxecmd
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cat /boot/grub/pxeboot.img core.img >grub.pxe
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@end group
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@end example
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Copy @file{grub.pxe}, @file{/boot/grub/*.mod}, and @file{/boot/grub/*.lst}
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to the PXE (TFTP) server, ensuring that @file{*.mod} and @file{*.lst} are
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accessible via the @file{/boot/grub/} path from the TFTP server root. Set
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the DHCP server configuration to offer @file{grub.pxe} as the boot file (the
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@samp{filename} option in ISC dhcpd).
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After GRUB has started, files on the TFTP server will be accessible via the
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@samp{(pxe)} device.
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The server and gateway IP address can be controlled by changing the
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@samp{(pxe)} device name to @samp{(pxe:@var{server-ip})} or
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@samp{(pxe:@var{server-ip}:@var{gateway-ip})}. Note that this should be
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changed both in the prefix and in any references to the device name in the
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configuration file.
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GRUB provides several environment variables which may be used to inspect or
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change the behaviour of the PXE device:
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@table @samp
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@item net_pxe_ip
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The IP address of this machine. Read-only.
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1026
@item net_pxe_mac
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The network interface's MAC address. Read-only.
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@item net_pxe_hostname
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The client host name provided by DHCP. Read-only.
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@item net_pxe_domain
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The client domain name provided by DHCP. Read-only.
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@item net_pxe_rootpath
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The path to the client's root disk provided by DHCP. Read-only.
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@item net_pxe_extensionspath
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The path to additional DHCP vendor extensions provided by DHCP. Read-only.
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@item net_pxe_boot_file
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The boot file name provided by DHCP. Read-only.
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@item net_pxe_dhcp_server_name
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The name of the DHCP server responsible for these boot parameters.
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Read-only.
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@item net_pxe_blksize
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The PXE transfer block size. Read-write, defaults to 512.
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@item pxe_default_server
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The default PXE server. Read-write, although setting this is only useful
1053
before opening a PXE device.
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@item pxe_default_gateway
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The default gateway to use when contacting the PXE server. Read-write,
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although setting this is only useful before opening a PXE device.
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@end table
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@node Serial terminal
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@chapter Using GRUB via a serial line
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command accepts many other options, so please refer to @ref{serial},
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for more details.
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The command @command{terminal} (@pxref{terminal}) chooses which type of
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The commands @command{terminal_input} (@pxref{terminal_input}) and
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@command{terminal_output} (@pxref{terminal_output} choose which type of
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terminal you want to use. In the case above, the terminal will be a
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serial terminal, but you can also pass @code{console} to the command,
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as @samp{terminal serial console}. In this case, a terminal in which
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@table @key
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@item Dell XPS M1530
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1125
85:3
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@item Asus EeePC 1005PE
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84:1 (unconfirmed)
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@end table
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To take full advantage of this function install GRUB into MBR.
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accessed by BIOS. Because of BIOS limitations, GRUB cannot distinguish
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between IDE, ESDI, SCSI, or others. You must know yourself which BIOS
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device is equivalent to which OS device. Normally, that will be clear if
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you see the files in a device or use the command @command{find}
1045
(@pxref{find}).
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you see the files in a device or use the command @command{search}
1140
(@pxref{search}).
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1141
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@menu
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* Device syntax:: How to specify devices
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represents using the first partition of the disk (or the boot sector
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of the partition when installing GRUB).
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If you enabled the network support, the special drive, @samp{(nd)}, is
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If you enabled the network support, the special drive @samp{(pxe)} is
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also available. Before using the network drive, you must initialize the
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network. @xref{Network}, for more information.
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@file{/boot/grub/grub.cfg} in the first partition of the first hard
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disk. If you omit the device name in an absolute file name, GRUB uses
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GRUB's @dfn{root device} implicitly. So if you set the root device to,
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say, @samp{(hd1,1)} by the command @command{root} (@pxref{root}), then
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@code{/boot/kernel} is the same as @code{(hd1,1)/boot/kernel}.
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say, @samp{(hd1,1)} by the command @samp{set root=(hd1,1)} (@pxref{set}),
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then @code{/boot/kernel} is the same as @code{(hd1,1)/boot/kernel}.
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@node Block list syntax
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of them can be entered on the command-line and can be used either
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anywhere in the menu or specifically in the menu entries.
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In rescue mode, only the @command{insmod} (@pxref{insmod}), @command{ls}
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(@pxref{ls}), @command{set} (@pxref{set}), and @command{unset}
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(@pxref{unset}) commands are normally available.
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@menu
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* Menu-specific commands::
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* General commands::
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@menu
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* serial:: Set up a serial device
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* terminal_input:: Manage input terminals
1448
* terminal_output:: Manage output terminals
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* terminfo:: Define terminal type
1349
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@end menu
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@samp{even} and defaults to @samp{no}.
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The serial port is not used as a communication channel unless the
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@command{terminal} command is used (@pxref{terminal}).
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@command{terminal_input} or @command{terminal_output} command is used
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(@pxref{terminal_input}, @pxref{terminal_output}).
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This command is only available if GRUB is compiled with serial
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support. See also @ref{Serial terminal}.
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@end deffn
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@node terminal_input
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@subsection terminal_input
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@deffn Command terminal_input [@option{--append}|@option{--remove}] @
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[terminal1] [terminal2] @dots{}
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List or select an input terminal.
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With no arguments, list the active and available input terminals.
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With @option{--append}, add the named terminals to the list of active input
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terminals; any of these may be used to provide input to GRUB.
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With @option{--remove}, remove the named terminals from the active list.
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With no options but a list of terminal names, make only the listed terminal
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names active.
1492
@end deffn
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@node terminal_output
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@subsection terminal_output
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@deffn Command terminal_output [@option{--append}|@option{--remove}] @
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[terminal1] [terminal2] @dots{}
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List or select an output terminal.
1501
1502
With no arguments, list the active and available output terminals.
1503
1504
With @option{--append}, add the named terminals to the list of active output
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terminals; all of these will receive output from GRUB.
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With @option{--remove}, remove the named terminals from the active list.
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With no options but a list of terminal names, make only the listed terminal
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names active.
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@end deffn
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@node terminfo
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@subsection terminfo
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1402
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* chainloader:: Chain-load another boot loader
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* cmp:: Compare two files
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* configfile:: Load a configuration file
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* cpuid:: Check for CPU features
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* crc:: Calculate CRC32 checksums
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* date:: Display or set current date and time
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* drivemap:: Map a drive to another
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* keystatus:: Check key modifier status
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* ls:: List devices or files
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* parttool:: Modify partition table entries
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* password:: Set a clear-text password
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* password_pbkdf2:: Set a hashed password
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* play:: Play a tune
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* pxe_unload:: Unload the PXE environment
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* reboot:: Reboot your computer
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* search:: Search devices by file, label, or UUID
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* set:: Set an environment variable
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* unset:: Unset an environment variable
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* uppermem:: Set the upper memory size
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@end menu
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1424
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1518
1664
@end deffn
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1520
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@node cpuid
1668
@subsection cpuid
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@deffn Command cpuid [-l]
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Check for CPU features. This command is only available on x86 systems.
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With the @option{-l} option, return true if the CPU supports long mode
1674
(64-bit).
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If invoked without options, this command currently behaves as if it had been
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invoked with @option{-l}. This may change in the future.
1678
@end deffn
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1680
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@node crc
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1682
@subsection crc
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@node help
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@subsection help
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@deffn Command help @option{--all} [pattern @dots{}]
1825
@deffn Command help [pattern @dots{}]
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1826
Display helpful information about builtin commands. If you do not
1667
specify @var{pattern}, this command shows short descriptions of most of
1668
available commands. If you specify the option @option{--all} to this
1669
command, short descriptions of rarely used commands (such as
1670
@ref{testload}) are displayed as well.
1827
specify @var{pattern}, this command shows short descriptions of all
1828
available commands.
1671
1829
1672
1830
If you specify any @var{patterns}, it displays longer information
1673
about each of the commands which match those @var{patterns}.
1831
about each of the commands whose names begin with those @var{patterns}.
1674
1832
@end deffn
1675
1833
1676
1834
1747
1905
@end deffn
1748
1906
1749
1907
1908
@node password
1909
@subsection password
1910
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@deffn Command password user clear-password
1912
Define a user named @var{user} with password @var{clear-password}.
1913
@xref{Security}.
1914
@end deffn
1915
1916
1917
@node password_pbkdf2
1918
@subsection password_pbkdf2
1919
1920
@deffn Command password_pbkdf2 user hashed-password
1921
Define a user named @var{user} with password hash @var{hashed-password}.
1922
Use @command{grub-mkpasswd-pbkdf2} (@pxref{Invoking grub-mkpasswd-pbkdf2})
1923
to generate password hashes. @xref{Security}.
1924
@end deffn
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1926
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1927
@node play
1751
1928
@subsection play
1752
1929
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@end deffn
1767
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1768
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@node pxe_unload
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@subsection pxe_unload
1948
1949
@deffn Command pxe_unload
1950
Unload the PXE environment (@pxref{Network}).
1951
1952
This command is only available on PC BIOS systems.
1953
@end deffn
1954
1955
1769
1956
@node reboot
1770
1957
@subsection reboot
1771
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@end deffn
1775
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@node search
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@subsection search
1966
1967
@deffn Command search @
1968
[@option{--file}|@option{--label}|@option{--fs-uuid}] @
1969
[@option{--set} var] [@option{--no-floppy}] name
1970
Search devices by file (@option{-f}, @option{--file}), filesystem label
1971
(@option{-l}, @option{--label}), or filesystem UUID (@option{-u},
1972
@option{--fs-uuid}).
1973
1974
If the @option{--set} option is used, the first device found is set as the
1975
value of environment variable @var{var}. The default variable is
1976
@samp{root}.
1977
1978
The @option{--no-floppy} option prevents searching floppy devices, which can
1979
be slow.
1980
1981
The @samp{search.file}, @samp{search.fs_label}, and @samp{search.fs_uuid}
1982
commands are aliases for @samp{search --file}, @samp{search --label}, and
1983
@samp{search --fs-uuid} respectively.
1984
@end deffn
1985
1986
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@node set
1778
1988
@subsection set
1779
1989
1791
2001
@end deffn
1792
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2003
2004
@node uppermem
2005
@subsection uppermem
2006
2007
This command is not yet implemented for GRUB 2, although it is planned.
2008
2009
2010
@node Security
2011
@chapter Authentication and authorisation
2012
2013
By default, the boot loader interface is accessible to anyone with physical
2014
access to the console: anyone can select and edit any menu entry, and anyone
2015
can get direct access to a GRUB shell prompt. For most systems, this is
2016
reasonable since anyone with direct physical access has a variety of other
2017
ways to gain full access, and requiring authentication at the boot loader
2018
level would only serve to make it difficult to recover broken systems.
2019
2020
However, in some environments, such as kiosks, it may be appropriate to lock
2021
down the boot loader to require authentication before performing certain
2022
operations.
2023
2024
The @samp{password} (@pxref{password}) and @samp{password_pbkdf2}
2025
(@pxref{password_pbkdf2}) commands can be used to define users, each of
2026
which has an associated password. @samp{password} sets the password in
2027
plain text, requiring @file{grub.cfg} to be secure; @samp{password_pbkdf2}
2028
sets the password hashed using the Password-Based Key Derivation Function
2029
(RFC 2898), requiring the use of @command{grub-mkpasswd-pbkdf2}
2030
(@pxref{Invoking grub-mkpasswd-pbkdf2}) to generate password hashes.
2031
2032
In order to enable authentication support, the @samp{superusers} environment
2033
variable must be set to a list of usernames, separated by any of spaces,
2034
commas, semicolons, pipes, or ampersands. Superusers are permitted to use
2035
the GRUB command line, edit menu entries, and execute any menu entry. If
2036
@samp{superusers} is set, then use of the command line is automatically
2037
restricted to superusers.
2038
2039
Other users may be given access to specific menu entries by giving a list of
2040
usernames (as above) using the @option{--users} option to the
2041
@samp{menuentry} command (@pxref{menuentry}). If the @option{--users}
2042
option is not used for a menu entry, then that entry is unrestricted.
2043
2044
Putting this together, a typical @file{grub.cfg} fragment might look like
2045
this:
2046
2047
@example
2048
@group
2049
set superusers="root"
2050
password_pbkdf2 root grub.pbkdf2.sha512.10000.biglongstring
2051
password user1 insecure
2052
2053
menuentry "May be run by any user" @{
2054
set root=(hd0,1)
2055
linux /vmlinuz
2056
@}
2057
2058
menuentry "Superusers only" --users "" @{
2059
set root=(hd0,1)
2060
linux /vmlinuz single
2061
@}
2062
2063
menuentry "May be run by user1 or a superuser" --users user1 @{
2064
set root=(hd0,2)
2065
chainloader +1
2066
@}
2067
@end group
2068
@end example
2069
2070
The @command{grub-mkconfig} program does not yet have built-in support for
2071
generating configuration files with authentication. You can use
2072
@file{/etc/grub.d/40_custom} to add simple superuser authentication, by
2073
adding @kbd{set superusers=} and @kbd{password} or @kbd{password_pbkdf2}
2074
commands.
2075
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2077
@node Troubleshooting
2078
@chapter Error messages produced by GRUB
2079
2080
@menu
2081
* GRUB only offers a rescue shell::
2082
@end menu
2083
2084
2085
@node GRUB only offers a rescue shell
2086
@section GRUB only offers a rescue shell
2087
2088
GRUB's normal start-up procedure involves setting the @samp{prefix}
2089
environment variable to a value set in the core image by
2090
@command{grub-install}, setting the @samp{root} variable to match, loading
2091
the @samp{normal} module from the prefix, and running the @samp{normal}
2092
command. This command is responsible for reading
2093
@file{/boot/grub/grub.cfg}, running the menu, and doing all the useful
2094
things GRUB is supposed to do.
2095
2096
If, instead, you only get a rescue shell, this usually means that GRUB
2097
failed to load the @samp{normal} module for some reason. It may be possible
2098
to work around this temporarily: for instance, if the reason for the failure
2099
is that @samp{prefix} is wrong (perhaps it refers to the wrong device, or
2100
perhaps the path to @file{/boot/grub} was not correctly made relative to the
2101
device), then you can correct this and enter normal mode manually:
2102
2103
@example
2104
@group
2105
# Inspect the current prefix (and other preset variables):
2106
set
2107
# Set to the correct value, which might be something like this:
2108
set prefix=(hd0,1)/grub
2109
set root=(hd0,1)
2110
insmod normal
2111
normal
2112
@end group
2113
@end example
2114
2115
However, any problem that leaves you in the rescue shell probably means that
2116
GRUB was not correctly installed. It may be more useful to try to reinstall
2117
it properly using @kbd{grub-install @var{device}} (@pxref{Invoking
2118
grub-install}). When doing this, there are a few things to remember:
2119
2120
@itemize @bullet{}
2121
@item
2122
Drive ordering in your operating system may not be the same as the boot
2123
drive ordering used by your firmware. Do not assume that your first hard
2124
drive (e.g. @samp{/dev/sda}) is the one that your firmware will boot from.
2125
2126
@item
2127
At least on BIOS systems, if you tell @command{grub-install} to install GRUB
2128
to a partition but GRUB has already been installed in the master boot
2129
record, then the GRUB installation in the partition will be ignored.
2130
2131
@item
2132
If possible, it is generally best to avoid installing GRUB to a partition
2133
(unless it is a special partition for the use of GRUB alone, such as the
2134
BIOS Boot Partition used on GPT). Doing this means that GRUB may stop being
2135
able to read its core image due to a file system moving blocks around, such
2136
as while defragmenting, running checks, or even during normal operation.
2137
Installing to the whole disk device is normally more robust.
2138
2139
@item
2140
Check that GRUB actually knows how to read from the device and file system
2141
containing @file{/boot/grub}. It will not be able to read from encrypted
2142
devices, nor from file systems for which support has not yet been added to
2143
GRUB.
2144
@end itemize
2145
2146
1794
2147
@node Invoking grub-install
1795
2148
@chapter Invoking grub-install
1796
2149
1858
2211
@end table
1859
2212
1860
2213
2214
@node Invoking grub-mkpasswd-pbkdf2
2215
@chapter Invoking grub-mkpasswd-pbkdf2
2216
2217
The program @command{grub-mkpasswd-pbkdf2} generates password hashes for
2218
GRUB (@pxref{Security}).
2219
2220
@example
2221
grub-mkpasswd-pbkdf2
2222
@end example
2223
2224
@command{grub-mkpasswd-pbkdf2} accepts the following options:
2225
2226
@table @option
2227
@item -c @var{number}
2228
@itemx --iteration-count=@var{number}
2229
Number of iterations of the underlying pseudo-random function. Defaults to
2230
10000.
2231
2232
@item -l @var{number}
2233
@itemx --buflen=@var{number}
2234
Length of the generated hash. Defaults to 64.
2235
2236
@item -s @var{number}
2237
@itemx --salt=@var{number}
2238
Length of the salt. Defaults to 64.
2239
@end table
2240
2241
1861
2242
@node Obtaining and Building GRUB
1862
2243
@appendix How to obtain and build GRUB
1863
2244
1895
2276
@end group
1896
2277
@end example
1897
2278
1898
Also, the latest version is available from the SVN. See
1899
@uref{http://savannah.gnu.org/svn/?group=grub} for more information.
2279
Also, the latest version is available using Bazaar. See
2280
@uref{http://www.gnu.org/software/grub/grub-download.en.html} for more
2281
information.
1900
2282
1901
2283
@node Reporting bugs
1902
2284
@appendix Reporting bugs
1976
2358
homepage}.
1977
2359
1978
2360
2361
@node Internals
2362
@appendix Hacking GRUB
2363
2364
@menu
2365
* Getting the source code::
2366
* Finding your way around::
2367
@end menu
2368
2369
2370
@node Getting the source code
2371
@section Getting the source code
2372
2373
GRUB is maintained using the @uref{http://bazaar-vcs.org/, Bazaar revision
2374
control system}. To fetch the primary development branch:
2375
2376
@example
2377
bzr get http://bzr.savannah.gnu.org/r/grub/trunk/grub
2378
@end example
2379
2380
The GRUB developers maintain several other branches with work in progress.
2381
Of these, the most interesting is the experimental branch, which is a
2382
staging area for new code which we expect to eventually merge into trunk but
2383
which is not yet ready:
2384
2385
@example
2386
bzr get http://bzr.savannah.gnu.org/r/grub/branches/experimental
2387
@end example
2388
2389
Once you have used @kbd{bzr get} to fetch an initial copy of a branch, you
2390
can use @kbd{bzr pull} to keep it up to date. If you have modified your
2391
local version, you may need to resolve conflicts when pulling.
2392
2393
2394
@node Finding your way around
2395
@section Finding your way around
2396
2397
Here is a brief map of the GRUB code base.
2398
2399
GRUB uses Autoconf, but not (yet) Automake. The top-level build rules are
2400
in @file{configure.ac}, @file{Makefile.in}, and @file{conf/*.rmk}. Each
2401
@file{conf/*.rmk} file represents a particular target configuration, and is
2402
processed into GNU Make rules by @file{genmk.rb} (which you only need to
2403
look at if you are extending the build system). If you are adding a new
2404
module which follows an existing pattern, such as a new command or a new
2405
filesystem implementation, it is usually easiest to grep @file{conf/*.rmk}
2406
for an existing example of that pattern to find out where it should be
2407
added.
2408
2409
Low-level boot code, such as the MBR implementation on PC BIOS systems, is
2410
in the @file{boot/} directory.
2411
2412
The GRUB kernel is in @file{kern/}. This contains core facilities such as
2413
the device, disk, and file frameworks, environment variable handling, list
2414
processing, and so on. The kernel should contain enough to get up to a
2415
rescue prompt. Header files for kernel facilities, among others, are in
2416
@file{include/}.
2417
2418
Terminal implementations are in @file{term/}.
2419
2420
Disk access code is spread across @file{disk/} (for accessing the disk
2421
devices themselves), @file{partmap/} (for interpreting partition table
2422
data), and @file{fs/} (for accessing filesystems). Note that, with the odd
2423
specialised exception, GRUB only contains code to @emph{read} from
2424
filesystems and tries to avoid containing any code to @emph{write} to
2425
filesystems; this lets us confidently assure users that GRUB cannot be
2426
responsible for filesystem corruption.
2427
2428
PCI and USB bus handling is in @file{bus/}.
2429
2430
Video handling code is in @file{video/}. The graphical menu system uses
2431
this heavily, but is in a separate directory, @file{gfxmenu/}.
2432
2433
Most commands are implemented by files in @file{commands/}, with the
2434
following exceptions:
2435
2436
@itemize
2437
@item
2438
A few core commands live in @file{kern/corecmd.c}.
2439
2440
@item
2441
Commands related to normal mode live under @file{normal/}.
2442
2443
@item
2444
Commands that load and boot kernels live under @file{loader/}.
2445
2446
@item
2447
The @samp{loopback} command is really a disk device, and so lives in
2448
@file{disk/loopback.c}.
2449
2450
@item
2451
The @samp{gettext} command lives under @file{gettext/}.
2452
2453
@item
2454
The @samp{loadfont} and @samp{lsfonts} commands live under @file{font/}.
2455
2456
@item
2457
The @samp{serial}, @samp{terminfo}, and @samp{background_image} commands
2458
live under @file{term/}.
2459
2460
@item
2461
The @samp{efiemu_*} commands live under @file{efiemu/}.
2462
@end itemize
2463
2464
There are a few other special-purpose exceptions; grep for them if they
2465
matter to you.
2466
2467
1979
2468
1980
2469
@node Copying This Manual
1981
2470
@appendix Copying This Manual
Loggerhead is a web-based interface for Breezy
Version: 2.0.1