[Fedora-xen] RHEL4 DomU Update Problem

Wed Oct 31 15:49:42 UTC 2007

Now it's really interesting. If I just try to boot the system with the disk labeled xvda, I get a huge series of kernel panics (see below.) If I change it to sda (in both the config file and grub) it looks like it might work, but then I get: 

Freeing unused kernel memory: 124k freed 
SCSI subsystem initialized 
Registering block device major 8 
register_blkdev: cannot get major 8 for sd 
xen_blk: can't get major 8 with name sd 
vbd vbd-2048: 19 xlvbd_add at /local/domain/0/backend/vbd/27/2048 
Registering block device major 8 
register_blkdev: cannot get major 8 for sd 
xen_blk: can't get major 8 with name sd 
vbd vbd-2048: 19 xlvbd_add at /local/domain/0/backend/vbd/27/2048 
XENBUS: Timeout connecting to device: device/vbd/2048 (state 6) 
device-mapper: 4.5.5-ioctl (2006-12-01) initialised: dm-devel at redhat.com 
Kernel panic - not syncing: Attempted to kill init! 

FYI, this wasn't a Xensource kernel before, it was actually a Fedora 5 kernel (2.6.15-1.2054_FC5xenU) I created a yum repository for RHEL4 with the Fedora kernel, and used it to set up the box. 

Kernel panics (lots of them, all the same): 
kernel BUG at arch/i386/mm/pgtable-xen.c:306! 
invalid operand: 0000 [#1] 
SMP 
Modules linked in: ext3 jbd dm_mod xenblk sd_mod scsi_mod 
CPU: 0 
EIP: 0061:[<c011163a>] Not tainted VLI 
EFLAGS: 00010282 (2.6.9-55.0.9.ELxenU) 
EIP is at pgd_ctor+0x1d/0x26 
eax: fffffff4 ebx: 00000000 ecx: f5392000 edx: 00000000 
esi: c19fdd80 edi: eca6aaa0 ebp: 00000001 esp: ecb3cd6c 
ds: 007b es: 007b ss: 0068 
Process 10-udev.hotplug (pid: 398, threadinfo=ecb3c000 task=ecb2a070) 
Stack: c0141b69 ecb4b000 c19fdd80 00000001 ecb4b000 eca6aaa0 c19fdd80 c19fde40 
c0141ceb c19fdd80 eca6aaa0 00000001 c19fdd80 eca6aaa0 ecb4b000 00000010 
00000001 000000d0 c1a1b080 0000000c c19fde08 c19fdd80 c0141eda c19fdd80 
Call Trace: 
[<c0141b69>] cache_init_objs+0x35/0x56 
[<c0141ceb>] cache_grow+0xfb/0x187 
[<c0141eda>] cache_alloc_refill+0x163/0x19c 
[<c01420f5>] kmem_cache_alloc+0x67/0x97 
[<c0111671>] pgd_alloc+0x17/0x336 
[<c01199d4>] mm_init+0xd7/0x116 
[<c01199e4>] mm_init+0xe7/0x116 
[<c0119c8a>] copy_mm+0xbb/0x396 
[<c0268f10>] __cond_resched+0x14/0x3c 
[<c011aa5a>] copy_process+0x6b5/0xb0b 
[<c011af9d>] do_fork+0x8a/0x16b 
[<c0107507>] error_code+0x2b/0x30 
[<c0105d2c>] sys_clone+0x24/0x28 
[<c010737f>] syscall_call+0x7/0xb 
Code: 74 02 66 a5 a8 01 74 01 a4 5e 5b 5e 5f c3 80 3d 04 07 2f c0 00 75 1c 6a 20 6a 00 ff 74 24 0c e8 ce 37 00 00 83 c4 0c 85 c0 74 08 <0f> 0b 32 01 b6 31 27 c0 c3 80 3d 04 07 2f c0 00 75 0d c7 44 24 
<0>Fatal exception: panic in 5 seconds 

----- Original Message ----- 
From: "Chris Lalancette" <clalance at redhat.com> 
To: "Jim Klein" <jklein at saugus.k12.ca.us> 
Cc: "fedora-xen" <fedora-xen at redhat.com> 
Sent: Tuesday, October 30, 2007 3:00:05 PM (GMT-0800) America/Los_Angeles 
Subject: Re: [Fedora-xen] RHEL4 DomU Update Problem 

Jim Klein wrote: 
> Interesting: 
> 
> XENBUS: Device with no driver: device/vbd/2048 
> XENBUS: Device with no driver: device/vif/0 
> Freeing unused kernel memory: 124k freed 
> device-mapper: 4.5.5-ioctl (2006-12-01) initialised: dm-devel at redhat.com 
> Kernel panic - not syncing: Attempted to kill init! 
> 
> Not sure where to go from here. 
> 

Believe it or not, those XENBUS errors are actually expected; the xenbus driver 
is loaded before the virtual disk/network drivers, and it sees that it has these 
nodes without drivers. 

However, that does lead me to an idea. If I remember correctly, the Xensource 
kernels have all of the drivers built-in, while we prefer to do things more 
modular. I'm guessing that you didn't have the right driver in 
/etc/modprobe.conf when the kernel was installed, so the initrd doesn't have the 
right drivers in it. So what you'll want to do is: 

1) Boot the RHEL-4 domU into the (working) Xen kernel. 
2) Edit /etc/modprobe.conf, and add: 

alias scsi_hostadapter xenblk 

3) Remove the RedHat RHEL-4 kernel (rpm -e), and install it again, which should 
re-generate the initrd with the right stuff in it. 

Chris Lalancette 
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