[Xen-users] Xen 3.1 not recognizing second SATA HD or DVD

["mark mclarnon" <mark.mclarnon@xxxxxxxxx>]

I have encountered a strange situation with Xen 3.1.0 that I cannot
seem to resolve. I wonder if  anyone in the community has experienced
anything similar. Assume for the moment that I have the proper CPU to
be running Xen in the first place. My situation is this:

Operating System: Debian Etch (Linux debian 2.6.18-6-686-bigmem)
Motherboard ASUS P5K 
8 GB RAM (hence bigmem kernel)
2 SATA Hard Drive 750 GB
2 SATA DVD Burner

Now
I am aware of the problems  with this particular board (P5K) and SATA
devices. Although there was no particular reason to choose SATA DVD
drives (a decision I now regret), I believe the use of 2 SATA HD was
ok. Incidentally, the only way I could get Debian onto the system was
using a USB key method.

NOTE: I am running the latest BIOS as downloaded from  ASUS support
today 02/25/08. Sorry I forget the rev number but its dated from Jan 08.

All
4 devices are connected to the 4 main mother board SATA channels (read
ICH9 connectors) and nothing is connected to the JMicron channel in the
back of the board. In addition to this, JMicron controller has been
disabled in the BIOS. The order of devices is:

1. SATA HD (/dev/sda)
2. SATA CDROM
3. SATA CDROM
4. SATA HD (/dev/sdb during normal Debian kernel)

I follow the instructions to build Xen from source:

# apt-get ..... (long list omitted here)
# make world
# make install

# update-rc.d xend defaults 20 21
# update-rc.d xendomains defaults 21 20

I
did not use any custom configuration or build options. Its at this
point that things get hairy. I see many google/Xen links that you must
build an initrd but the recommended way of doing so differs quite a
bit. Some links claim you should use mkinitrd, some claim yaird. Others
claim mkinitramfs and still others claim  update-initramfs. Initially
I    believe I used mkinitramfs as follows:

# depmod 2.6.18-xen
# mkinitramfs -o /boot/initrd.img-2.6.18-xen 2.6.18-xen

The next step was to run:

# update-grub

This automatically adds the following stanza to /etc/grub/menu.lst:

title        Xen 3.1.0 / Debian GNU/Linux, kernel 2.6.18-xen


root        (hd0,0)
kernel        /boot/xen-3.1.0.gz
module        /boot/vmlinuz-2.6.18-xen root=/dev/sda1 ro console=tty0
module        /boot/initrd.img-2.6.18-xen
savedefault

Coincidentally, my existing stanza was:


title        Debian GNU/Linux, kernel 2.6.18-6-686-bigmem
root        (hd0,0)
kernel        /boot/vmlinuz-2.6.18-6-686-bigmem root=/dev/sda1 ro 
initrd        /boot/initrd.img-2.6.18-6-686-bigmem
savedefault


Note the root=/dev/sda1 in each case. At this point, I reboot and
attempt to start the machine with a Xen kernel. Depending on how I have
the P5K BIOS setting "SATA Configuration" (detailed in the P5K user
manual section 4.3.5) the machine either fails to boot (when set with
the SATA Enhanced setting) or boots successfully (with the SATA Compatible setting) but never sees the second SATA HD or second DVD writer. In
short, the devices connected to the 3rd and 4th ICH9 SATA connectors
don't get recognized. The kernel boot messages mention /dev/hda then /dev/hdc immediately.

NOTE: When SATA Configuration is set to Compatible, the only way Xen will
boot is if I change the root=/dev/sda1 to read root=/dev/hda1.
 
Whats
even more interesting (to me at least) is that when booting with the
Xen kernel, the boot device that used to be known as /dev/sda is
recognized by the kernel as /dev/hda. Yet files such as /etc/fstab
still reference /dev/sda1! Does the SCSI subsystem provide a mapping of
some type from /dev/sda to /dev/hda? Is it a softlink in the /dev
directory?

In desperation, I have tried grub options such as all-generic-ide
and irqpoll to get the second drives recognized but the system never
seems to boot properly listing errors with "lost interrupt hda" and the
like. The second HD and DVD writer seem to show up as /dev/sde and
/dev/sdg (if I recall correctly).

My questions are:

1. Is attempting to use a second HD and DVD writer a lost cause?
2. Why does the Xen kernel skip the recognition of the second HD and DVD writer?
3. Why if the boot log reports my boot device was recognized as /dev/hda does my system still boot and reference /dev/sda? 


4. Why must /etc/grub/menu.lst be changed but not /etc/fstab?
5. Could this entire problem be attributed to the lack of judgment when procuring a Xen compatible motherboard?

Has anyone seen this situation before?


Mark
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