Bug 114015 – xen domU fails to boot

• Product: Gentoo Linux
• Status: RESOLVED UPSTREAM

[Description gbugs 2005-11-30 04:55:32 UTC]

Moving from xen-3.0.0_pre20041027 to xen-3.0.0_pre20051128 keeping existing
configs for both Dom0 and DomU kernels result in a non-bootable DomUs (Kernels
were recompiled to include upgraded patches).  There is a kernel oops during
DomU boot - see additional info below.

It apears (for me at least) that it is possible to work around the problem by
using my Dom0 kernel as a DomU kernel (although why that helps is unclear).



Reproducible: Always
Steps to Reproduce:
Start a DomU in Xen. 'Kernel panic - not syncing: VFS: Unable to mount root fs
on unknown-block(0,0)'
Actual Results:  
DomU fails to boot, there is a kernel oops, some compaints about being unable to
get a blod device, and finally a 

Expected Results:  
Booted normally (as before)

Boot log from failing DomU

Started domain ttylinux
Linux version 2.6.12.6.5-xen (root@xen01) (gcc version 3.3.6 (Gentoo 3.3.6,
ssp-3.3.6-1.0, pie-8.7.8)) #19 SMP Tue Nov 29 11:29:45 EST 2005
BIOS-provided physical RAM map:
 Xen: 0000000000000000 - 0000000002000000 (usable)
40MB LOWMEM available.
IRQ lockup detection disabled
Built 1 zonelists
Kernel command line:  root=/dev/sda1
Initializing CPU#0
PID hash table entries: 256 (order: 8, 4096 bytes)
Xen reported: 3053.412 MHz processor.
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
vmalloc area: c3000000-fbef5000, maxmem 34000000
Memory: 28664k/40960k available (2209k kernel code, 4032k reserved, 712k data,
152k init, 0k highmem)
Checking if this processor honours the WP bit even in supervisor mode... Ok.
Mount-cache hash table entries: 512
CPU: Trace cache: 12K uops, L1 D cache: 8K
CPU: L2 cache: 512K
Enabling fast FPU save and restore... done.
Enabling unmasked SIMD FPU exception support... done.
Checking 'hlt' instruction... disabled
Brought up 1 CPUs
NET: Registered protocol family 16
xen_mem: Initialising balloon driver.
SCSI subsystem initialized
Grant table initialized
audit: initializing netlink socket (disabled)
audit(1133283177.769:0): initialized
devfs: 2004-01-31 Richard Gooch ([e-mail])
devfs: boot_options: 0x0
Installing knfsd (copyright (C) 1996 [e-mail]).
Initializing Cryptographic API
i8042.c: No controller found.
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered
Floppy drive(s): fd0 is unknown type 15 (usb?), fd1 is unknown type 15 (usb?)
Failed to obtain physical IRQ 6
floppy0: no floppy controllers found
loop: loaded (max 8 devices)
WARNING: Failed to register Xen virtual console driver as 'tty1'
Event-channel device installed.
netfront: Initialising virtual ethernet driver.
mice: PS/2 mouse device common for all mice
NET: Registered protocol family 2
Registering block device major 8
register_blkdev: cannot get major 8 for sd
xen_blk: can't get major 8 with name sd
Unable to handle kernel NULL pointer dereference at virtual address 00000104
 printing eip:
c026244b
*pde = ma 00000000 pa 55555000
Oops: 0002 [#1]
SMP
Modules linked in:
CPU:    0
EIP:    0061:[<c026244b>]    Not tainted VLI
EFLAGS: 00010086   (2.6.12.6.5-xen)
EIP is at blk_start_queue+0xb/0x60
eax: 00000000   ebx: 00000000   ecx: fbffc000   edx: 00000000
esi: c0282350   edi: c0098b2b   ebp: c039b4e0   esp: c002bee4
ds: 007b   es: 007b   ss: 0069
Process xenwatch (pid: 7, threadinfo=c002a000 task=c0021a20)
Stack: 00000003 c2412000 c0282623 00000000 c2412000 c028254b c2412000 00000000
       00000004 00000000 00000200 c2412000 c0352099 c002bf30 c03648e0 c036e631
       c002bf34 00000000 0000a000 00000000 00000200 c045b480 c027cd8c c2412000
Call Trace:
 [<c0282623>] kick_pending_request_queues+0x23/0x40
 [<c028254b>] connect+0x11b/0x130
 [<c027cd8c>] otherend_changed+0x8c/0x90
 [<c027c1f4>] xenwatch_thread+0x124/0x150
 [<c0132de0>] autoremove_wake_function+0x0/0x60
 [<c0132de0>] autoremove_wake_function+0x0/0x60
 [<c027c0d0>] xenwatch_thread+0x0/0x150
 [<c013290a>] kthread+0xba/0xc0
 [<c0132850>] kthread+0x0/0xc0
 [<c0107915>] kernel_thread_helper+0x5/0x10
Code: 83 ec 04 8b 44 24 08 89 04 24 ff 50 60 59 c3 90 81 44 24 04 a0 00 00 00 e9
f3 25 00 00 8d 76 00 83 ec 08 89 5c 24 04 8b 5c 24 0c <f0> 0f ba b3 04 01 00 00
02 f0 0f ba ab 04 01 00 00 06 19 c0 85
 <6>IP: routing cache hash table of 512 buckets, 4Kbytes
TCP established hash table entries: 2048 (order: 2, 16384 bytes)
TCP bind hash table entries: 2048 (order: 2, 16384 bytes)
TCP: Hash tables configured (established 2048 bind 2048)
ip_conntrack version 2.1 (320 buckets, 2560 max) - 216 bytes per conntrack
ip_tables: (C) 2000-2002 Netfilter core team
ipt_recent v0.3.1: Stephen Frost <[e-mail]>. 
http://snowman.net/projects/ipt_recent/
arp_tables: (C) 2002 David S. Miller
NET: Registered protocol family 1
NET: Registered protocol family 17
Bridge firewalling registered
VFS: Cannot open root device "sda1" or unknown-block(0,0)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

[Comment 1 Chris Bainbridge (RETIRED) 2005-11-30 06:53:42 UTC]

It's odd that your dom0 works. Maybe domU is configured differently? Try
unmerge, rm -rf /usr/src/xensources, then emerge again, make menuconfig from
scratch. The rm -rf will be necessary to clean out all old sources (bug #110752,
xen-sources currently installs everything into the same dir)

If that doesn't work please report this bug upstream, either on the xen-devel
mailing list, or on xensource bugzilla.

[Comment 2 gbugs 2005-11-30 08:31:29 UTC]

Already did the clean compile (and a number of other things) - posted to xen dev
list as well, but no response thus far.  Could it just have been a 'bad'
snapshot (I presume the gentoo patches etc. are just taken from Xen's nightly
drops)?  Might it be worth a version bump in that case?