Re: [Qemu-devel] [RFC PATCH v1 0/4] Handle memory hotplug errors from guest OS.

[tangchen <tangchen@cn.fujitsu.com>]

Hi,

Would anyone help to review this patch-set ?
I'm not quit sure if this is a suitable way solve this problem.

Thanks.


On 08/27/2014 04:14 PM, tangchen wrote:
>
> Forgot to mention, this patch-set is based on the following patch-set:
>
> [RESEND PATCH v3 0/8] QEmu memory hot unplug support.
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg253018.html
>
> Thanks.
>
> On 08/27/2014 04:09 PM, Tang Chen wrote:
>> When doing memory hotplug, QEmu is not aware of guest OS error when 
>> hotplugging
>> memory devices. Even if guest OS failed to hot-add memory, the pc-dimm
>> device will be added to QEmu. Even if guest OS failed to hot-remove 
>> memory,
>> QEmu will remove the pc-dimm device.
>>
>> An example is: for a Linux guest, the Linux kernel limited that the 
>> size of
>> hot-added memory should be mutiple of memory section (128MB by default).
>> If we add 130MB memory, the Linux kernel won't add it. We are not able
>> to handle the size check in QEmu commmand line because different OS may
>> have different limits.
>>
>> And also, QEmu outputs nothing but guest OS failed to hot-add memory 
>> will
>> confuse users. We should at least report an error.
>>
>> So, we should report the error to users, and cancel the memory hotplug
>> progress in QEmu.
>>
>> QEmu thread sends a SCI to guest OS and return immediately. The vcpu 
>> thread
>> will emulate ACPI hardware operations. So this patch-set introduces a 
>> wait
>> condition variable to synchronize these two threads.
>>
>> Tang Chen (4):
>>    Use macro to define ACPI notification event.
>>    Add event handling for memory device insertion.
>>    Introduce wait condition to catch guest OS memory hotplug error.
>>    Handle memory hotplug error from guest OS in QEmu.
>>
>>   hw/acpi/memory_hotplug.c | 146 
>> +++++++++++++++++++++++++++++++++++++++++++++--
>>   include/hw/acpi/acpi.h   |  15 ++++-
>>   2 files changed, 153 insertions(+), 8 deletions(-)
>>
>
> .
>