[Qemu-devel] vcpu hotplug status

[Qemu-devel] vcpu hotplug status

[William Dauchy]

Hi,

I wanted to test vcpu hotplug. When adding a cpu I'm getting
"qdev_create_from_info: Assertion `bus->allow_hotplug' failed."
I went through a discussion about the subject here
http://lists.nongnu.org/archive/html/qemu-devel/2010-08/msg00999.html
To make sure whether it was working, I hard-coded "allow_hotplug = 1";
the guest is now able to have more vpcus without any trouble (removing
vcpus did not seem to work though).
Since it definitively not a solution, I wanted to have a status about
the subject or if I was missing something in my configuration since it
works with a dirty workaround.
I would be also pleased to get some tips to fix the code.

Regards,
-- 
William

[Qemu-devel] Re: vcpu hotplug status

[William Dauchy]

On Wed, Mar 16, 2011 at 11:17 AM, William Dauchy <wdauchy@gmail.com> wrote:
> I wanted to test vcpu hotplug. When adding a cpu I'm getting
> "qdev_create_from_info: Assertion `bus->allow_hotplug' failed."
> I went through a discussion about the subject here
> http://lists.nongnu.org/archive/html/qemu-devel/2010-08/msg00999.html
> To make sure whether it was working, I hard-coded "allow_hotplug = 1";
> the guest is now able to have more vpcus without any trouble (removing
> vcpus did not seem to work though).
> Since it definitively not a solution, I wanted to have a status about
> the subject or if I was missing something in my configuration since it
> works with a dirty workaround.
> I would be also pleased to get some tips to fix the code.

Any thoughts? Or perhaps my message was lost among patches...

-- 
William

Re: [Qemu-devel] Re: vcpu hotplug status

[Gleb Natapov]

On Sat, Mar 19, 2011 at 12:25:38PM +0100, William Dauchy wrote:
> On Wed, Mar 16, 2011 at 11:17 AM, William Dauchy <wdauchy@gmail.com> wrote:
> > I wanted to test vcpu hotplug. When adding a cpu I'm getting
> > "qdev_create_from_info: Assertion `bus->allow_hotplug' failed."
> > I went through a discussion about the subject here
> > http://lists.nongnu.org/archive/html/qemu-devel/2010-08/msg00999.html
> > To make sure whether it was working, I hard-coded "allow_hotplug = 1";
> > the guest is now able to have more vpcus without any trouble (removing
> > vcpus did not seem to work though).
> > Since it definitively not a solution, I wanted to have a status about
> > the subject or if I was missing something in my configuration since it
> > works with a dirty workaround.
> > I would be also pleased to get some tips to fix the code.
> 
> Any thoughts? Or perhaps my message was lost among patches...
> 
Even patches are lost among patches those days. The problem you describe
is known. Both of them actually (non working vcpu remove is the second
one). I am not aware of any effort to fix them. I am more concern about
second problem though. bus->allow_hotplug is not fixed because of
laziness on developers part, but non working vcpu remove is caused by us not
understanding how cpu hot-plug works in Linux on x86.

--
			Gleb.