Xen users - Apr 2009 - domU custom kernel: Kernel panic - not syncing: No init found. Try passing init= option to kernel.

Hello,

To compile a custom kernel, I downloaded 2.6.29.1 from kernel.org and 
followed the tutorial at: 
http://wiki.xensource.com/xenwiki/Kernel.org_Linux_on_Xen

Used a supposedly working .config file for the compilation (generated by 
my provider to compile his xenU kernels), set /dev/xvd* device nodes 
both in the domU conf file (disk, root):

disk = [ ''phy:/dev/mapper/alveox-fhsslash,/dev/xvdb1,w'', 
''phy:/dev/mapper/alveox-fhsswap,xvdb2,w'' ]
root = "/dev/xvdb1"


and its /etc/fstab:

proc /proc proc defaults 0 0
/dev/xvdb1 / reiserfs defaults 0 1
/dev/xvdb2 none swap sw 0 0


When booting the VM, I get a kernel panic at this point:
...
ReiserFS: xvdb1: found reiserfs format "3.6" with standard journal
ReiserFS: xvdb1: using ordered data mode
ReiserFS: xvdb1: journal params: device xvdb1, size 8192, journal first 
block 18, max trans len 1024, max batch 900, max commit age 30, max 
trans age 30
ReiserFS: xvdb1: checking transaction log (xvdb1)
ReiserFS: xvdb1: replayed 9 transactions in 1 seconds
ReiserFS: xvdb1: Using r5 hash to sort names
ReiserFS: xvdb1: Removing [190 26878 0x0 SD]..done
ReiserFS: xvdb1: Removing [190 26872 0x0 SD]..done
ReiserFS: xvdb1: Removing [190 26845 0x0 SD]..done
ReiserFS: xvdb1: Removing [190 26804 0x0 SD]..done
ReiserFS: xvdb1: Removing [190 26797 0x0 SD]..done
ReiserFS: xvdb1: There were 5 uncompleted unlinks/truncates. Completed
VFS: Mounted root (reiserfs filesystem) on device 202:17.
Freeing unused kernel memory: 268k freed
Kernel panic - not syncing: No init found.  Try passing init= option to 
kernel.


Cannot figure why its not booting. It seems to find and mount root 
correctly....
When I mount the filesystem manually, /sbin/init appears there.

Tried it with 3 different kernels from kernel.org: 2.6.29.1, 2.6.21.27, 
2.6.25.7 --> same error.

Problem does not seem to come from the dom0, when I use the kernel 
provided by my provider, the same filesystems are mounted just fine, the 
VM boots, here is what I get instead of the kernel panic:

VFS: Mounted root (reiserfs filesystem).
Freeing unused kernel memory: 256k freed
INIT: version 2.86 booting

Any help, or pointers where the problem may come from, appreciated....

Cheers

David


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On Sat, Apr 25, 2009 at 9:07 PM, Alveox Services <alveox@alveox.com>
wrote:
> VFS: Mounted root (reiserfs filesystem) on device 202:17.
> Freeing unused kernel memory: 268k freed
> Kernel panic - not syncing: No init found.  Try passing init= option to
> kernel.
>
>
> Cannot figure why its not booting. It seems to find and mount root
> correctly....
> When I mount the filesystem manually, /sbin/init appears there.
You could try passing "init=/sbin/init". That would go in
domU''s
grub.conf (if you use pygrub) or "extra" line on domU config (if
kernel is on dom0).

Another possibility is that the kernel and userland has mismatched arch. Like :
- 32bit kernel on 64bit userland, or
- 64bit kernel, with 32bit compatibility turned off, on 32bit userland
(this happened to me once).

Regards,

Fajar

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Hi Fajar,

Thanks for your response
> Another possibility is that the kernel and userland has mismatched arch.
Like :
> - 32bit kernel on 64bit userland, or
>   
That was it... I am compiling on a 64 bit system, was compiling the 
kernel in 64 bit while userland (including /sbin/init) is 32 bit.

It boots fine when compiled with:
 make ARCH=i386 menuconfig
 make ARCH=i386


Thanks a lot !



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On Sun, Apr 26, 2009 at 12:36 AM, Alveox Services <alveox@alveox.com>
wrote:
> That was it... I am compiling on a 64 bit system, was compiling the kernel
> in 64 bit while userland (including /sbin/init) is 32 bit.
>
> It boots fine when compiled with:
> make ARCH=i386 menuconfig
> make ARCH=i386
If that''s the case you should be able to use 64bit kernel as well IF
you set
CONFIG_IA32_EMULATION=y

Regards,

Fajar

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