Re: [Qemu-devel] [RFC PATCH v4 01/11] exec: Remove cpu from cpus list during cpu_exec_exit()

[Zhu Guihua <zhugh.fnst@cn.fujitsu.com>]

On 09/09/2015 01:52 PM, Bharata B Rao wrote:
> On Fri, Sep 04, 2015 at 03:31:24PM +1000, David Gibson wrote:
>> On Thu, Aug 06, 2015 at 10:57:07AM +0530, Bharata B Rao wrote:
>>> CPUState *cpu gets added to the cpus list during cpu_exec_init(). It
>>> should be removed from cpu_exec_exit().
>>>
>>> cpu_exec_init() is called from generic CPU::instance_finalize and some
>>> archs like PowerPC call it from CPU unrealizefn. So ensure that we
>>> dequeue the cpu only once.
>>>
>>> Instead of introducing a new field CPUState.queued, I could have used
>>> CPUState.cpu_index to check if the cpu is already dequeued from the list.
>>> Since that doesn't work for CONFIG_USER_ONLY, I had to add a new field.
>>>
>>> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
>> This seems reasonable to me, but I'm wondering how x86 cpu hotplug /
>> unplug is working without it.
> x86 hotplug/unplug code currently resides in Zhu's git tree
> (git://github.com/zhugh/qemu). They are removing the CPU from the list
> explicitly in x86 CPU's instance_finalize routine.

Sorry, my git tree is git://github.com/zhuguihua/qemu

Now there was no progress about topology, so we don't know what will happen
in x86. I am not sure whether we will take this method finally.

Thanks,
Zhu

>
> Since we add CPU to the list in cpu_exec_init(), I thought it makes
> sense to remove it in cpu_exec_exit().
>
> May be it makes sense to separately purse this patch and the next one
> so that other archs are also taken into account correctly.
>
> Regards,
> Bharata.
>
>
>