Re: Fallback for SATA and IDE drives when booting from a CD?

[adrian15]

Russel Hill escribió:
> I posted the following on grub-devel before I realized that this was
> the better list for it...
>
> We are booting from a CD which needs to forward to a bootable hard
> drive (if possible). The hard drive might be SATA, might be IDE.
>
> My current menu.lst looks something like this:
>
> #########################################
> timeout 10
> default 0
> fallback 1 2
>
> title boot from SATA drive
> root (hd0,0)
> kernel /vmlinuz root=/dev/sda2 panic=5
> boot
>
> title boot from IDE drive
> root (hd0,0)
> kernel /vmlinuz root=/dev/hda2 panic=5
> boot
>
> title Boot from CD
> root (cd)
> kernel /boot/vmlinuz root=/dev/ram0 init=/linuxrc
> initrd /boot/initrd.img
> boot
> #########################################
>
> The only difference between entries 0 and 1 is in the
> "root=/dev/?da2".  If we were booting from writable media, we could
> use "default savedefault" and "savedefault fallback" commands to chain
> from one entry to the other after a kernel panic. Unfortunately,
> that's not the situation. As it is this menu.lst works with SATA
> drives but not with PATA or IDE drives. I can switch this around by
> reordering the entries (or modifying default and fallback) but I can't
> seem to get
>
> Is there a way for grub to substitute the correct /dev/* depending on
> whether the drive is SATA or not?

Well... you can modify the grub source code... make him search the first
/etc/fstab file in every hard disk (I have the code) and then, this is
the difficult part you have to parse fstab file in order to search "/"
and extract sda2, hda2, sda5 or whatever so that you can use it later.

All of this means C coding and for me it is not a priority for my Super
Grub Disk.


> Even better would be a way to make this work when booting from a CD:
>
> #########################################
> timeout 10
> default 0
> fallback 1
>
> title boot from hard drive
> rootnoverify (hd0)
> chainloader +1

Does not work?
> title Boot from CD
> root (cd)
> kernel /boot/vmlinuz root=/dev/ram0 init=/linuxrc
> initrd /boot/initrd.img
> boot
> #########################################
>
> Can this be made to work? If so, what am I missing?

Does the Boot & Tools -> Boot Hard Disk  option from Super Grub Disk
cdrom (Available at http://supergrub.forjamari.linex.org ) NOT boot your
first hard disk ?

Maybe you have not anything installed on the MBR... maybe an easiest
solution if the filesystem is ext3 would be to install grub into the
linux partition boot sector,...

why do you use a cdrom to boot ?

adrian15