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From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
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Date: Mon, 13 Jun 2016 18:15:29 +0800
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Subject: Re: [dpdk-dev] [PATCH] virtio: fix allocating virtnet_rx not mem
	aligned
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On 6/13/2016 5:21 PM, 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?

I guess clang does such optimization when length is a 32-byte aligned 
immediate number. May need more information here.

Thanks,
Jianfeng

>
> 	--yliu