Re: [Xen-devel] [RFC] Re-introduce VCPUOP_register_vcpu_info back for PVHVM guests. (v1)

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Mon, Apr 22, 2013 at 8:24 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 17.04.13 at 18:24, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
>> On 17/04/13 17:23, Jan Beulich wrote:
>>>>>> On 17.04.13 at 17:31, George Dunlap <George.Dunlap@xxxxxxxxxxxxx> wrote:
>>>> On Tue, Apr 16, 2013 at 10:09 PM, Konrad Rzeszutek Wilk
>>>> <konrad.wilk@xxxxxxxxxx> wrote:
>>>>> Hey Jan,
>>>>>
>>>>> While I've been digging around CPU hotplug for PVHVM I noticed an oddity
>>>>> when running with different versions of hypervisor. I found out that the
>>>>> big change you did in Xen 4.2 of splitting the PV and HVM arch structure
>>>>> introduce the regression wherein VCPUOP_register_vcpu_info will not
>>>>> work for PVHVM guests.
>>>>>
>>>>> Interestingly enough if I introduce this back to the hypervisor the
>>>>> CPU hotplug path gets even more broken for PVHVM :-).. But that is a Linux
>>>>> problem.
>>>> Except that we really don't want to be trashing people's existing,
>>>> working versions of Linux, especially if they're distro-provided
>>>> kernels.  I haven't tested a distro kernel yet, but for my own
>>>> locally-built 2.6.37 kernel, this c/s breaks it running in PVHVM mode.
>>> Hmm - that's minimally a reason to not backport it to 4.2, but
>>> perhaps even a reason to revert it from staging.
>>
>> Hold off on reverting it -- I thought I had clearly shown it to be the
>> c/s that breaks things, but now it's not so clear... really frustrating
>> dealing w/ the build system right now...
>
> What's the status on this? Sander over the weekend reported
> another issue with the patch, so I'm clearly going to keep this off
> the stable trees for the time being, but of course we also should
> have a clear picture for unstable.

[Re-sending with the full cc list]

I sent an e-mail Friday afternoon saying that my results were spurious
-- so please act as you would if I had never sent the e-mail. :-)

 -George

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