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2002-01-15 Yoshinori K. Okuji <okuji@gnu.org>

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* docs/grub.texi (Preset Menu): New chapter.
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okuji 2002-01-15 10:28:18 +00:00
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@ -1,3 +1,7 @@
2002-01-15 Yoshinori K. Okuji <okuji@gnu.org>
* docs/grub.texi (Preset Menu): New chapter.
2002-01-15 Yoshinori K. Okuji <okuji@gnu.org>
* docs/grub.texi: Added some text about JFS and XFS.

75
docs/grub.texi
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@ -99,6 +99,7 @@ This edition documents version @value{VERSION}.
* Configuration:: Writing your own configuration file
* Network:: Downloading OS images from a network
* Serial terminal:: Using GRUB via a serial line
* Preset Menu:: Embedding a configuration file into GRUB
* Security:: Improving the security
* Images:: GRUB image files
* Filesystem:: Filesystem syntax and semantics
@ -1242,10 +1243,15 @@ example about a BOOTP configuration:
foo:ht=1:ha=63655d0334a7:ip=145.71.35.127:\
:bf=/nbgrub:\
:tc=.allhost:\
:T150="/tftpboot/menu.lst.foo":
:T150="(nd)/tftpboot/menu.lst.foo":
@end group
@end example
Note that you should specify the drive name @code{(nd)} in the name of
the configuration file. That is because you can change the root drive
before downloading the configuration from the TFTP server, when the
preset menu feature is used (@pxref{Preset Menu}).
See the manual about your BOOTP/DHCP server, for more information. The
exact syntax should differ from the example, more or less.
@ -1297,10 +1303,69 @@ compatible with VT100 by default. This is true for most terminal
emulators nowadays, but you should pass the option @option{--dumb} to
the command, if your terminal emulator is not VT100-compatible or
implements few VT100 escape sequences. If you specify the option, then
GRUB doesn't provide you with the menu interface, because the menu
requires several fancy features for your terminal. Instead, GRUB only
gives you the hidden menu interface and the command-line interface
(@pxref{Interface}).
GRUB provides you with an alternative menu interface, because the normal
menu requires several fancy features for your terminal.
@node Preset Menu
@chapter Embedding a configuration file into GRUB
GRUB supports @dfn{preset menu} which is 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 nice to run
the commands @command{serial} (@pxref{serial}) and @command{terminal}
(@pxref{terminal}) sooner than anything else at the start-up time.
It is slightly complicated how the preset menu works:
@enumerate
@item
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.
@item
GRUB checks if the configuration file is available. Note that this check
is performed @strong{regardless of the existence of the preset
menu}. The configuration file is loaded, even after the preset menu was
loaded.
@item
When 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.
@end enumerate
To enable the preset menu feature, you must specify a file to the
configure script with the option @option{--enable-preset-menu}. The file
has the same semantics as normal configuration files
(@pxref{Configuration}).
Another point you should take care is that the diskless support
(@pxref{Diskless}) diverts the preset menu. Diskless images embed a
preset menu to execute the command @command{bootp} (@pxref{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:
@example
@group
# Set up the serial terminal, first of all.
serial --unit=0 --speed=19200
terminal --timeout=0 serial
# Initialize the network.
dhcp
@end group
@end example
@node Security