[Qemu-devel] disable clocksource=kvm-clock

[Qemu-devel] disable clocksource=kvm-clock

[Peter Lieven]

hi,

is it possible to avoid detection of clocksource=kvm_clock in a linux 
guest by
patching the qemu-kvm binary?
i would like to be able to avoid a guest detecting kvm-clock until bug 
#584516
is fixed without modifying all guest systems and reverting that later.

thanks,
peter

[Qemu-devel] Re: disable clocksource=kvm-clock

[Avi Kivity]

On 06/01/2010 04:12 PM, Peter Lieven wrote:
> hi,
>
> is it possible to avoid detection of clocksource=kvm_clock in a linux 
> guest by
> patching the qemu-kvm binary?
> i would like to be able to avoid a guest detecting kvm-clock until bug 
> #584516
> is fixed without modifying all guest systems and reverting that later.
>

Newer qemu-kvm's will have this feature (using -cpu ...,-kvmclock).

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

Re: [Qemu-devel] Re: disable clocksource=kvm-clock

[Peter Lieven]

Avi Kivity wrote:
> On 06/01/2010 04:12 PM, Peter Lieven wrote:
>> hi,
>>
>> is it possible to avoid detection of clocksource=kvm_clock in a linux 
>> guest by
>> patching the qemu-kvm binary?
>> i would like to be able to avoid a guest detecting kvm-clock until 
>> bug #584516
>> is fixed without modifying all guest systems and reverting that later.
>>
>
> Newer qemu-kvm's will have this feature (using -cpu ...,-kvmclock).
>
with latest git, i can supply this switch, but

cat /sys/devices/system/clocksource/clocksource0/current_clocksource

still shows kvm_clock in an opensuse 11.2 64-bit or an ubuntu 10.04 
64-bit guest.

Re: [Qemu-devel] Re: disable clocksource=kvm-clock

[Avi Kivity]

On 06/01/2010 04:57 PM, Peter Lieven wrote:
> Avi Kivity wrote:
>> On 06/01/2010 04:12 PM, Peter Lieven wrote:
>>> hi,
>>>
>>> is it possible to avoid detection of clocksource=kvm_clock in a 
>>> linux guest by
>>> patching the qemu-kvm binary?
>>> i would like to be able to avoid a guest detecting kvm-clock until 
>>> bug #584516
>>> is fixed without modifying all guest systems and reverting that later.
>>>
>>
>> Newer qemu-kvm's will have this feature (using -cpu ...,-kvmclock).
>>
> with latest git, i can supply this switch, but
>
> cat /sys/devices/system/clocksource/clocksource0/current_clocksource
>
> still shows kvm_clock in an opensuse 11.2 64-bit or an ubuntu 10.04 
> 64-bit guest.

Try again with tomorrow's git, I sent out a patchset earlier today that 
fixes this.

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

Re: [Qemu-devel] Re: disable clocksource=kvm-clock

[Peter Lieven]

Avi Kivity wrote:
> On 06/01/2010 04:57 PM, Peter Lieven wrote:
>> Avi Kivity wrote:
>>> On 06/01/2010 04:12 PM, Peter Lieven wrote:
>>>> hi,
>>>>
>>>> is it possible to avoid detection of clocksource=kvm_clock in a 
>>>> linux guest by
>>>> patching the qemu-kvm binary?
>>>> i would like to be able to avoid a guest detecting kvm-clock until 
>>>> bug #584516
>>>> is fixed without modifying all guest systems and reverting that later.
>>>>
>>>
>>> Newer qemu-kvm's will have this feature (using -cpu ...,-kvmclock).
>>>
>> with latest git, i can supply this switch, but
>>
>> cat /sys/devices/system/clocksource/clocksource0/current_clocksource
>>
>> still shows kvm_clock in an opensuse 11.2 64-bit or an ubuntu 10.04 
>> 64-bit guest.
>
> Try again with tomorrow's git, I sent out a patchset earlier today 
> that fixes this.
>
avi, i do not know whats going on. but if i supply -cpu xxx,-kvmclock 
the guest
still uses kvm-clock, but it seems bug #584516 is not triggered...
thats weird...

br,
peter


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Re: [Qemu-devel] Re: disable clocksource=kvm-clock

[Avi Kivity]

On 06/01/2010 05:06 PM, Peter Lieven wrote:
>
> avi, i do not know whats going on. but if i supply -cpu xxx,-kvmclock 
> the guest
> still uses kvm-clock, but it seems bug #584516 is not triggered...
> thats weird...

I guess that bug was resolved in qemu-kvm.git.  Likely 1a03675db1, but 
it appears to be part of 0.12 too, so not sure.

What qemu-kvm were you using previously?

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

Re: [Qemu-devel] Re: disable clocksource=kvm-clock

[Peter Lieven]

Avi Kivity wrote:
> On 06/01/2010 05:06 PM, Peter Lieven wrote:
>>
>> avi, i do not know whats going on. but if i supply -cpu xxx,-kvmclock 
>> the guest
>> still uses kvm-clock, but it seems bug #584516 is not triggered...
>> thats weird...
>
> I guess that bug was resolved in qemu-kvm.git.  Likely 1a03675db1, but 
> it appears to be part of 0.12 too, so not sure.
>
> What qemu-kvm were you using previously?
>
i'm using qemu-kvm git from today (aa22e82).

bug #585113 seems to be fixed (this was the irq nobody cared error with 
virtio_blk or e1000)
bug #584516 is still there, but if I set - cpu  xxx,-kvmclock it is not 
triggered. the guest
shows current_clocksource = kvm_clock, but migration seems to succeed 
(at least the ~20
times i tested it since you told me about the flag)

do you have a clue what fixed bug #585113. i would like to backport it 
to 0.12.4

Re: [Qemu-devel] Re: disable clocksource=kvm-clock

[Peter Lieven]

Avi Kivity wrote:
> On 06/01/2010 04:57 PM, Peter Lieven wrote:
>> Avi Kivity wrote:
>>> On 06/01/2010 04:12 PM, Peter Lieven wrote:
>>>> hi,
>>>>
>>>> is it possible to avoid detection of clocksource=kvm_clock in a 
>>>> linux guest by
>>>> patching the qemu-kvm binary?
>>>> i would like to be able to avoid a guest detecting kvm-clock until 
>>>> bug #584516
>>>> is fixed without modifying all guest systems and reverting that later.
>>>>
>>>
>>> Newer qemu-kvm's will have this feature (using -cpu ...,-kvmclock).
>>>
>> with latest git, i can supply this switch, but
>>
>> cat /sys/devices/system/clocksource/clocksource0/current_clocksource
>>
>> still shows kvm_clock in an opensuse 11.2 64-bit or an ubuntu 10.04 
>> 64-bit guest.
>
> Try again with tomorrow's git, I sent out a patchset earlier today 
> that fixes this.
>
i don't see it in the git, do you mean:
[PATCH 0/5] Use more cpuid bits from upstream

thanks,
peter