Node:Preset Menu, Next:Security, Previous:Serial terminal, Up:Top
GRUB supports 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
serial (see serial) and
(see terminal) sooner than anything else at the start-up time.
It is slightly complicated how the preset menu works:
To enable the preset menu feature, you must specify a file to the
configure script with the option
--enable-preset-menu. The file
has the same semantics as normal configuration files
Another point you should take care is that the diskless support
(see Diskless) diverts the preset menu. Diskless images embed a
preset menu to execute the command
bootp (see 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
# Set up the serial terminal, first of all. serial --unit=0 --speed=19200 terminal --timeout=0 serial # Initialize the network. dhcp