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From: "Xie, Huawei" <huawei.xie@intel.com>
To: "dev@dpdk.org" <dev@dpdk.org>,
	Thomas Monjalon <thomas.monjalon@6wind.com>
Subject: Re: [dpdk-dev] [PATCH] virtio: fix the vq size issue
Date: Fri, 10 Jul 2015 14:05:45 +0000	[thread overview]
Message-ID: <C37D651A908B024F974696C65296B57B0F56C2C7@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <C37D651A908B024F974696C65296B57B0F5504FB@SHSMSX101.ccr.corp.intel.com>

Thomas:
Could we roll back that commit or apply Changchun's patch?

/Huawei

On 7/1/2015 11:53 PM, Xie, Huawei wrote:
> On 7/1/2015 3:49 PM, Ouyang Changchun wrote:
>> This commit breaks virtio basic packets rx functionality:
>>   d78deadae4dca240e85054bf2d604a801676becc
>>
>> The QEMU use 256 as default vring size, also use this default value to calculate the virtio
>> avail ring base address and used ring base address, and vhost in the backend use the ring base
>> address to do packet IO.
>>
>> Virtio spec also says the queue size in PCI configuration is read-only, so virtio front end
>> can't change it. just need use the read-only value to allocate space for vring and calculate the
>> avail and used ring base address. Otherwise, the avail and used ring base address will be different
>> between host and guest, accordingly, packet IO can't work normally.
> virtio driver could still use the vq_size to initialize avail ring and
> use ring so that they still have the same base address.
> The other issue is vhost use  index & (vq->size -1) to index the ring.
>
>
> Thomas:
> This fix works but introduces slight change with original code. Could we
> just rollback that commit?
>
> d78deadae4dca240e85054bf2d604a801676becc
>
>
>> Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
>> ---
>>  drivers/net/virtio/virtio_ethdev.c | 14 +++-----------
>>  1 file changed, 3 insertions(+), 11 deletions(-)
>>
>>
>
>


  parent reply	other threads:[~2015-07-10 14:05 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-01  7:48 Ouyang Changchun
2015-07-01  8:55 ` Xu, Qian Q
2015-07-01 15:53 ` Xie, Huawei
2015-07-02  0:29   ` Ouyang, Changchun
2015-07-02  2:01     ` Xie, Huawei
2015-07-02  2:16       ` Ouyang, Changchun
2015-07-02  9:15         ` Xie, Huawei
2015-07-03  1:53           ` Ouyang, Changchun
2015-07-10 14:05   ` Xie, Huawei [this message]
2015-07-10 14:11     ` Thomas Monjalon
2015-07-13  1:40       ` Ouyang, Changchun
2015-07-07  2:32 ` Ouyang, Changchun
2015-07-17 10:42   ` Thomas Monjalon
2015-07-17 16:27 ` Stephen Hemminger
2015-07-18 12:11   ` Ouyang, Changchun
2015-07-20 15:47     ` Stephen Hemminger
2015-07-20  3:40   ` Xu, Qian Q
2015-07-20  6:18     ` Ouyang, Changchun
2015-07-20 10:42       ` Thomas Monjalon
2015-07-21  5:23         ` Ouyang, Changchun
2015-07-20 15:30       ` Stephen Hemminger

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