# Xen boot issue

## db_404

Having problems booting a DomU host under the latest portage version of Xen - config was working OK, but after installing new version (and rebuilding kernels to use new patchset - using the same config as before) I am unable to boot my virtual hosts.  The Dom0 host worked OK.  Boot log posted below (notice the kernel oops).

```

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 (rgooch@atnf.csiro.au)

devfs: boot_options: 0x0

Installing knfsd (copyright (C) 1996 okir@monad.swb.de).

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 <sfrost@snowman.net>.  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)

```

----------

## kox

Same problem by me.

I have used the same config for domU kernel as in the previous version.

Any idea?

----------

## db_404

I'm currently working around the problem by using my dom0 kernel as a domU (which works for reasons unknown...).

I'm assuming it's just a problem with the current snapshot - I'll probably file a bug, as it's happening to >1 individual.

----------

## kox

Iam still playing with the latest ebuild. Dom0 boot without problems.

I tried to boot domU with the guest kernel compiled with xen-3.0.0-pre20051122 and it booted without problem.

Really interesting problem  :Smile: 

----------

## ElCondor

 *kox wrote:*   

> I tried to boot domU with the guest kernel compiled with xen-3.0.0-pre20051122 and it booted without problem.

 

Are different versions of (xen-patched) kernels going together with those of xen? or how do I find out with one go together?

I installed 3.0.0_pre20051128 with kernel 2.6.12.5-r4 - domUs Ooops at boot as you described. keeping this kernel and using xen 3.0.0_pre20051122 there is no Ooops, but still the "VFS: Cannot open root device "sda1" or unknown-block(0,0) ". switching to xen 3.0.0_pre20051027 caused the dom0 to reboot immediatly.

is there a working combination of xen and xen-sources in portage? and if there is - which combination  is it? 

Thanks in advance

* ElCondor pasa *

----------

## db_404

I assume the xen & xen sources go together.  Which would make sense as then xen assumes a patched kernel, and patches are xen release specific.  Booting with an previous xen patchset version of the kernel (at least for Dom0) has never worked for me (won't boot at all - hangs after Xen boot, never reaches linux kernel).

With the previous release I _had_ to build the Dom0 as non-SMP and DomU as SMP or I got the VFS panic in the domUs.  In the current version I can't get the DomU to boot at all, so I'm just re-using my Dom0 kernel for the DomUs which seems to be working.

I suspect the Gentoo builds are based of the nightly drops so presumably there is a fair chance of breakage - seemingly a little more than I'd like (even for a ~x86 package).

----------

