Re: Support for RAID in grub-setup

[Jeroen Dekkers]

At Fri, 28 Jul 2006 00:20:42 +0200,
Yoshinori K. Okuji wrote:
> 
> On Monday 24 July 2006 15:36, Jeroen Dekkers wrote:
> > Grub-setup will ask Linux for the members of the RAID array that is
> > given as destination device. It will then install on the MBRs of those
> > devices and embed core.img after MBR. If it can't embed the core image
> > it will fail, I'm not sure whether we should support reading core.img
> > from a RAID array...
> 
> Personally, I like to see that every part can be read from a RAID device, but 
> maybe not so important in reality....

It would be possible to calculate how to write the image to the file
so it ends up being a consecutive image on the physical disk. But I
think it's not worth the trouble, especially given that we can always
embed the kernel if we keep the size below the 31k.

> > I let grub-setup put the RAID device directly into the prefix and put
> > -2 in grub_install_dos_part. I've modified make_install_device() in
> > init.c to leave the prefix alone when grub_install_dos_part is -2.
> 
> So, if my understanding is correct, core.img is read from a single disk, but 
> the rest is handled in a RAID device, right?

Yes, core.img is embedded after the MBR on the specific disk.  If you
can boot from a disk, it's a pretty safe to assume thatt you can also
read core.img for the same disk. Core.img includes the RAID module and
that is used to read everything else it needs.

Jeroen Dekkers