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Date: Mon, 13 Jun 2016 17:51:46 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: Jianfeng Tan <jianfeng.tan@intel.com>
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Subject: Re: [dpdk-dev] [PATCH] virtio: fix allocating virtnet_rx not mem
 aligned
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On Mon, Jun 13, 2016 at 05:21:01PM +0800, Yuanhan Liu wrote:
> On Sun, Jun 12, 2016 at 02:29:42PM +0000, Jianfeng Tan wrote:
> > Compile DPDK with clang, below line in virtio_rxtx.c could be
> > optimized with four "VMOVAPS ymm, m256".
> >   memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
> > 
> > This instruction requires memory address is 32-byte aligned.
> > Or, it leads to segfault.
> 
> That looks like a dangerous optimization to me. If that's the case,
> doesn't it mean we have to make sure the address is always aligned
> properly while calling memset?

Above is just a side note. Anyway, I think making sure vq is cache
aligned is good here. So, I will apply it. BTW, do you mind if I
squash your 2 fixes into Huawei's Rx/Tx split commit? His commit is
not pushed to upstream yet, therefore I can still do rebase: I'm
thinking it's better to have one working commit other than one broken
commit followed with several fixing commits. And of course, I will
mention your contribution in the commit log.

	--yliu