Re: [Qemu-devel] [PATCH 1/2] memory: allow zero size for adjust_endianness()

[Jason Wang]

On 08/26/2015 10:51 PM, Greg Kurz wrote:
> On Wed, 26 Aug 2015 15:21:59 +0100
> Peter Maydell <address@hidden> wrote:
>
>> On 26 August 2015 at 11:04, Jason Wang <address@hidden> wrote:
>>> Wildcard mmio eventfd use zero size, but it will lead abort() since it
>>> was illegal in adjust_endianness(). Fix this by allowing zero size.
>>>
>>> Cc: Greg Kurz <address@hidden>
>>> Cc: Paolo Bonzini <address@hidden>
>>> Signed-off-by: Jason Wang <address@hidden>
>> This seems to me like a bug in the caller. Why would anything
>> try to call into the memory subsystem to do a zero-size
>> transaction?
>>
>> thanks
>> -- PMM
>>
> Here's the patch which needs zero-size eventfd:
>
> http://patchwork.ozlabs.org/patch/509428/
>
> Cheers.
>
> --
> Greg
>

Yes, this is because we want to use wildcard mmio eventfd (which
requires size to be zero) to speed up virtio 1.0 mmio.