64bit guest thinks it is 32bit in kvm-86 - Intel only

64bit guest thinks it is 32bit in kvm-86 - Intel only

[Josh Wilsdon]

I have been fighting with a problem with kvm-86 now for a while and I
wanted to see if this was a known issue or anyone had suggestions as
to where to look.  These tests are being run on an Intel Core 2 Quad
Q8400 with 4GB of RAM.  The host OS is Ubuntu 9.04 using the
2.6.28-11-server kernel that comes with Ubuntu 9.04.  I've narrowed
the problem down to kvm-86 not running 64 bit kernels in 64bit mode.
I have been testing with the stock Ubuntu 9.04 64-bit server kernel
"vmlinuz-2.6.28-11-server".  The minimal command I've been able to use
to reproduce this is:

    sudo kvm -M pc -cpu qemu64 -kernel /boot/vmlinuz-2.6.28-11-server
-vnc 0.0.0.0:0

With the kernel modules and userland from both kvm-84 and kvm-85
(compiled with the same options which just say --prefix=/usr and
--kerneldir=<my kernel source>) these options work fine and the kernel
starts up.  I'm not passing any filesystem so it hangs, but it boots.
With kvm-86 and the same options/configuration, the kernel refuses to
boot with the error message:

    "This kernel requires an x86-64 CPU, but only detected an i686 CPU.
     Unable to boot - please use a kernel appropriate for your CPU."

it works on all 3 versions when I add the -no-kvm option.

I have also tested this on an AMD Athlon 64 X2 4200+ CPU.  On that
machine, all three of the kvm versions tested worked correctly both
with and without the -no-kvm option.  I used the same binaries, the
same kernel and same set of modules on both systems, just kvm_intel
loaded on one and kvm_amd on the other.

Is there a known issue with the kvm_intel module in kvm-86 and 64bit
guests?  If not, any suggestions as to what I should look at next?

Thanks,
-Josh


-- 
Josh Wilsdon
LayerBoom Systems
joshw@layerboom.com
http://layerboom.com

Re: 64bit guest thinks it is 32bit in kvm-86 - Intel only

[Mark McLoughlin]

On Sun, 2009-05-24 at 19:45 -0700, Josh Wilsdon wrote:

> the kernel refuses to boot with the error message:
> 
>     "This kernel requires an x86-64 CPU, but only detected an i686 CPU.
>      Unable to boot - please use a kernel appropriate for your CPU."

This should fix it:

  http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=8fa3b3ce6e

Cheers,
Mark.

Re: 64bit guest thinks it is 32bit in kvm-86 - Intel only

[Josh Wilsdon]

>> the kernel refuses to boot with the error message:
>>
>>     "This kernel requires an x86-64 CPU, but only detected an i686 CPU.
>>      Unable to boot - please use a kernel appropriate for your CPU."
>
> This should fix it:
>
>  http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=8fa3b3ce6e

Yes, that fixed it!  Thanks!

Out of curiosity, is there a reason that this was not included in the
kvm-86 release, even though the date on the commit is May 12?

-Josh

-- 
Josh Wilsdon
LayerBoom Systems
joshw@layerboom.com
http://layerboom.com

Re: 64bit guest thinks it is 32bit in kvm-86 - Intel only

[Avi Kivity]

Josh Wilsdon wrote:
>>> the kernel refuses to boot with the error message:
>>>
>>>     "This kernel requires an x86-64 CPU, but only detected an i686 CPU.
>>>      Unable to boot - please use a kernel appropriate for your CPU."
>>>       
>> This should fix it:
>>
>>  http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=commitdiff;h=8fa3b3ce6e
>>     
>
> Yes, that fixed it!  Thanks!
>
> Out of curiosity, is there a reason that this was not included in the
> kvm-86 release, even though the date on the commit is May 12?
>   

I think it's the authorship date, not the commit date.

-- 
error compiling committee.c: too many arguments to function