I managed to boot the HURD last night!
As I wrote before, the GRUB boot floppy provided with gnu-0.2.tar.gz
doesn't work off my LS120 IDE floppy. Neither does the 0.5 release of
GRUB, which I built from source. However, after many failed
experiments, I managed to modify grub-0.5's boot sector so that it
works with both my ordinary and my IDE floppies. (I include the patch
below, and I will tell Erich about my experiences.)
Having got grub-0.5 to boot from floppy I found that GRUB can't see the
partition in which I unpacked the Hurd ("Disk geometry error"). This
was no surprise, as the partition starts more than 2 GB into the disc.
I was pleased to notice, however, that GRUB can see at least one of my
logical partitions: when I type "root= (hd0,4)" it finds an "ext2fs"
which is presumably my Linux /usr partition in /dev/hda5.
So, all I simply did was copy the Hurd's /boot/gnumach and
/boot/serverboot to a new directory /hurd.boot/ in my Linux root
partition, /dev/hda2, which is visible for the BIOS and GRUB. (I also
copied /boot/servers.boot, but that was unnecessary, I think.) I then
gave these instructions to GRUB:
root= (hda0,1)
kernel= /hurd.boot/gnumach root=hd0s6 -s
module= /hurd.boot/serverboot
boot
And it worked!
(It did, however, take quite a few attempts to get those partition
descriptions correct; this seems to be real defect in the existing
documentation.)
I didn't really try to do anything with the Hurd after booting it, as
it's good to go to bed after a success rather than a failure. It's also
good to get six hours of sleep, when possible ...
Edmund
My GRUB patch:
It's just a hack, not a serious attempt to improve the software, but it
did give a floppy that boots off both my ordinary and my IDE floppy drives.
In grub-0.5/stage1/stage1.S the patch is:
< andb $BIOS_HD_FLAG, %al
<
< /* jz floppy_probe */
< .byte 0x0f, 0x84; REL(floppy_probe)
---
> orb $BIOS_HD_FLAG, %al
>
> /* jz floppy_probe */
> .byte 0x0f, 0x84; REL(floppy_probe)
If you prefer to patch the binary boot sector, the change is:
< 24 80
---
> 0c 80
That's at address 0x55 in grub-0.5/bin/stage1; the address is
different, no doubt, in the Hurd's boot floppy, which is based on an
earlier release of GRUB, but the same change might work for that too.
Edmund
