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Date: Thu, 27 Aug 2015 12:50:19 +0800
From: Jason Wang <jasowang@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] memory: allow zero size for
	adjust_endianness()
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To: Greg Kurz <gkurz@linux.vnet.ibm.com>, Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>, "Michael S. Tsirkin" <mst@redhat.com>



On 08/26/2015 10:51 PM, Greg Kurz wrote:
> On Wed, 26 Aug 2015 15:21:59 +0100
> Peter Maydell <peter.maydell@linaro.org> wrote:
>
>> On 26 August 2015 at 11:04, Jason Wang <jasowang@redhat.com> 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 <gkurz@linux.vnet.ibm.com>
>>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> 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.