Booting on systems where BIOS does not pass boot drive correctly

[Matthew Garrett]

I've recently obtained a Toshiba Libretto U100. It appears that the BIOS 
does not pass the boot drive correctly, and so grub only works if the 
"d" argument is given to grub's install command.

The attached patch does the following:

a) If the "d" argument is not given, saves the source drive in a new 
field in the stage1 header
b) If stage1 is unable to find the boot drive, check whether the source 
drive was saved. If so, set that as the boot drive and try to boot 
again
c) If booting still fails, error out

The only time that this code should run is in the case of the BIOS 
failing to provide the boot drive. It will not be executed if the "d" 
command is given to install.

-- 
Matthew Garrett | address@hidden

grub.diff
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