Re: unhandled wrmsr

[Dave Young <hidave.darkstar@gmail.com>]

On Thu, Jun 3, 2010 at 5:52 PM, Dave Young <hidave.darkstar@gmail.com> wrote:
> On Thu, Jun 3, 2010 at 5:30 PM, Andre Przywara <andre.przywara@amd.com> wrote:
>> Dave Young wrote:
>>>
>>> On Wed, Jun 2, 2010 at 8:45 PM, Andre Przywara <andre.przywara@amd.com>
>>> wrote:
>>>>
>>>> Dave Young wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> With today's git version (qemu-kvm), I got following message in kernel
>>>>> dmesg
>>>>>
>>>>> [168344.215605] kvm: 27289: cpu0 unhandled wrmsr: 0x198 data 0
>>>>
>>>> Are you sure about that?
>>>
>>> Sure
>>>
>>> 0x198 is an Intel architectural perfmon MSR and it
>>>>
>>>> is read-only. The Linux kernel source I grep'ed obeys this and does only
>>>> rdmsr.
>>>> You can work around this by changing the error to a warning with:
>>>> # modprobe kvm ignore_msrs=1
>>>
>>> with this param, appear following warning:
>>> kvm: 28520: cpu0 ignored wrmsr: 0x198 data 0
>>
>> As suspected. Did the boot succeed, then?
>
> Yes, boot ok even without "ignore_msrs=1"
>
>>>
>>>> I'd like to see more details about the guest Linux kernel, at least the
>>>> version you used to see why there is a wrmsr on this address. Best is you
>>>> provide the kernel (just the vmlinuz file) somewhere so that we can
>>>> reproduce this. Also the qemu-kvm command line would be interesting.
>>>
>>> Actually I tried different guest image, recreate this problem is easy.
>>>
>>> one of them is slackware 13.0 kernel version 2.6.29.6, you can download
>>> from:
>>> http://www.slackware.at/data/slackware64-13.0/kernels/huge.s/
>>
>> Ah, nice to meet the other Slackware user ;-)
>
> me too :)
>
>>
>>> kvm cmdline:
>>> qemu-system-x86_64 -net nic -net tap,ifname=tap0,script=no slack64.img
>>
>> I tried:
>> $ x86_64-softmmu/qemu-system-x86_64 -kernel /boot/vmlinuz-huge-2.6.29.6
>> -nographic -append "console=ttyS0,115200n8" -cpu
>> core2duo,model=26,stepping=5,vendor=GenuineIntel
>> This booted fine.
>> Sadly I had no access to an Intel box this morning, so I had to use vendor
>> override, but I guess this misses some features which an original Intel box
>> has.
>> Can you post the /proc/cpuinfo output from the guest? It seems that some
>> feature bits trigger the behavior in the guest. The host was an Xeon5520,
>> right?

Forgot to tell host cpu is Intel Core2 Duo  E7500

>
> Here it is:
>
> processor       : 0
> vendor_id       : GenuineIntel
> cpu family      : 6
> model           : 2
> model name      : QEMU Virtual CPU version 0.12.50
> stepping        : 3
> cpu MHz         : 2925.956
> cache size      : 4096 KB
> fpu             : yes
> fpu_exception   : yes
> cpuid level     : 4
> wp              : yes
> flags           : fpu de pse tsc msr pae mce cx8 apic sep mtrr pge mca
> cmov pse36 clflush mmx fxsr sse sse2 syscall nx lm up rep_good pni
> cx16 hypervisor lahf_lm
> bogomips        : 5854.74
> clflush size    : 64
> cache_alignment : 64
> address sizes   : 40 bits physical, 48 bits virtual
> power management:
>
>>
>> Regards,
>> Andre.
>>
>> --
>> Andre Przywara
>> AMD-Operating System Research Center (OSRC), Dresden, Germany
>> Tel: +49 351 448-3567-12
>>
>>
>
>
>
> --
> Regards
> dave
>



-- 
Regards
dave