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disable clocksource=kvm-clock

DISCUSSION Peter Lieven 2 participants 8 messages Jun 1, 2010 – Jun 2, 2010 KVM

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Peter Lieven

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#0 lore raw

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

#1 lore raw
Quoted 7 lines · 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.

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

Signature · 1 line
error compiling committee.c: too many arguments to function
author
#2 lore raw
Quoted 11 lines · Avi Kivity
Quoted 7 lines · 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.

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.

#3 lore raw
Quoted 10 lines · Peter Lieven
Quoted 9 lines · Avi Kivity
Quoted 7 lines · 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.

Quoted 7 lines
Quoted 2 lines

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.

Signature · 1 line
error compiling committee.c: too many arguments to function
author
#4 lore raw
Quoted 13 lines · Avi Kivity
Quoted 12 lines · Peter Lieven
Quoted 11 lines · Avi Kivity
Quoted 7 lines · 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.

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

Quoted 8 lines
Quoted 5 lines

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

Signature · 16 lines
Mit freundlichen Grüßen/Kind Regards

Peter Lieven

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#5 lore raw
Quoted 4 lines · Peter Lieven

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?

Signature · 1 line
error compiling committee.c: too many arguments to function
author
#6 lore raw
Quoted 10 lines · Avi Kivity
Quoted 4 lines · Peter Lieven

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

author
#7 lore raw
In reply to Avi Kivity
Quoted 13 lines · Avi Kivity
Quoted 12 lines · Peter Lieven
Quoted 11 lines · Avi Kivity
Quoted 7 lines · 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.

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

Quoted 8 lines
Quoted 5 lines

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