Re: Problem booting OS on IDE PCI adaptor card with Grub in MBR of hda

On Sunday 16 July 2006 06:26, Mikkel L. Ellertson wrote:
nigel henry wrote:
I'v actually just got FC1 to boot from the main bootloader in hda, but
that is from a kernel entry, not the chainloader. All I get from trying
to chainload is a grub prompt.

Running /sbin/grub I tried different drives to see if grub> root (hdx,0)
would find somewhere to put FC1's bootloader. grub> root (hd2,0) printed
the following, after also running grub> setup (hd2).

grub> root (hd2,0)
Filesystem type is ext2fs, partition type 0x83

grub> setup (hd2)
Checking if "/boot/grub/stage1" exists... yes
Checking if "/boot/grub/stage2" exists... yes
Checking if "/boot/grub/e2fs_stage1_5" exists... yes
Running "embed /boot/grub/e2fs_stage1_5 (hd2)"... 15 sectors are
embedded. succeeded
Running "install /boot/grub/stage1 (hd2) (hd2)1+15 p
(hd2,0)/boot/grub/stage2 /boot/grub/grub.conf"... succeeded
Done.

There's some weird stuff going on here, as (hd2) hdc, is the cdwriter,
and when I ran grub> setup (hd2) the writers light was flickering quite a
bit, but as you can see from the output above, the bootloader installed
ok.

The CD is not a hard drive. Grub does not care about the interface,
just about the BIOS numbering. A SCSI hard drive would also show up
as (hdx). For that matter, my SATA hard drive is (hd0) under Grub,
and /dev/sda under Linux.

Yes the BIOS numbering compared to the /dev entries, caused the confusion,
resulting in the ridiculous scenario of trying to force Grub to install on
(hd4) a truly non-existant disc.

Another thing that is a bit weird, is that the kernel entries in
grub.conf, apart from the latest from fedora legacy show a strange entry
after label=/. Again, as below.
LABEL=/ hdc=ide-scsi (perhaps this has something to do with Win ME
identifying the IDE PCI adaptor card as a scsi controller)

I've never seen that before.

NO, it is using SCSI emulation for the CD-ROM drive, so that you can
access it as a SCSI CD. This used to be used a lot with CD writers.
FC1 is probably old enough that it still needs it. I don't remember
what version of the kernel/cdrecord let you use the IDE command set
to control a CD writer.

Quite what the situation is with the cdwriter now, I don't know. It
wasn't showing up in the mobo's BIOS before. Only the cdrom drive (hdd),
and the dvdrom (hdg) which I couldn't boot a distro from were there.

As I can boot an FC1 kernel from the main bootloader, the harddrive on
the IDE PCI adaptor card is obviously accessable, but there is obviously
some problem with the BIOS regarding drive ID's. Webmin on FC1 still
shows the harddrive on the IDE PCI adaptor card as IDE device E, and yet
the mobo's BIOS is identifying this same harddrive as hdc.

Anyway, the only problem left now is accessing the Grub menu. I've been
back into FC1, and changed the splashimage from (hd4,0) to (hd2,0), but
still only get the Grub prompt when trying to chainload to (hd2,0) hdc1,
aka hde1.

Nigel.

One thing to keep firmly in mind is that the /dev/hdx device entries
are not the same as the BIOS hard drive or Grub numbering. As far as
the BIOS is concerned, the first hard drive it finds is device 80,
then second one 81, and so on. It gets interesting when you have
both SCSI and IDE drives in the same system, because if the system
is set to boot off the SCSI controller, then the first SCSI drive
will be BIOS 80, Grub (hd0). Also, if you tell the BIOS to boot off
a hard drive other then the first one, the numbering changes. I have
not checked into it, but it would be interesting to see how the
drives are numbered when you boot off of a USB drive.

Thankfully I only have IDE drives, no doubt more knowledge of how Grub works,
would have saved a lot of time and hair removal.

Mikkel

Thanks for all your friendly help.

Nigel.
--

Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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