Re: [cobalt-developers] Qube2: booting different kernel?

[Tim Hockin <thockin@xxxxxxxxxx>]

Brian Warner wrote:

>  Jump_to_Real_Kernel: disk error, trying BFD again
>  Decompressing  done
>  Jump_to_Real_Kernel: disk error, trying BFD again
>  get_root_dev: nr_boot_failures 0x00000002 exceeds maxtries 0x00000002 for boot_index 0x00000000

Not sure what is going on here - perhaps teh older kernel doesn't
understand a newer ext2 format?  Shouldn't be....

> So my question to the experts is: how does the Qube2 boot? Is there a block
> table (ala 'lilo') that has to match the physical placement of the kernel?
> Does the prom know how to parse an ext2 filesystem and thus search for
> /boot/vmlinux.gz (or /usr/games/.doug, I've heard rumored, if you press a
> magic set of buttons and stand on one foot..). Is there a restriction on the
> partition size or location of the kernel? Is there any way to get the Qube2
> prom to boot from a particular file? (I've heard that more recent proms are
> more flexible about this).

The kernel is (by default) /boot/vmlinux.gz - the system will try to
boot that file...

at the rom prompt:

bfd /path/to/vmlinux.gz

> I'm guessing that there is a two-stage loader involved (given the two
> "Decompressing done" messages that appear when it boots successfully), and
> that the first is probably in ROM, and probably mounts /dev/hda1 and looks for
> /boot/vmlinux.gz . (and in fact the "bfd" command appears to take a filename,
> because if I boot the original disk with anything other than "bfd" or "bfd
> /boot/vmlinux.gz" it fails). But are there restrictions as to how that drive
> must be partitioned, or sized? Any idea what I'm missing?

No restrictions that I know of...being an unvalidated drive, I can't
even guess what is going on.  As for your guesses about the bootloader,
that is about correct. :)