From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zoltan Kiss <zoltan.kiss@linaro.org>
Subject: ixgbe_recv_scattered_pkts_vec split_flags question
Date: Tue, 21 Jul 2015 16:09:59 +0100
Message-ID: <55AE60C7.8050406@linaro.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
To: "dev@dpdk.org" <dev@dpdk.org>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-wg0-f41.google.com (mail-wg0-f41.google.com [74.125.82.41])
 by dpdk.org (Postfix) with ESMTP id 238005A41
 for <dev@dpdk.org>; Tue, 21 Jul 2015 17:10:01 +0200 (CEST)
Received: by wgav7 with SMTP id v7so93792326wga.2
 for <dev@dpdk.org>; Tue, 21 Jul 2015 08:10:01 -0700 (PDT)
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

Hi,

I have a question regarding split_flags in this question. It's defined 
as an array of 1 byte unsigned ints:

uint8_t split_flags[RTE_IXGBE_VPMD_RX_BURST] = {0};

RTE_IXGBE_VPMD_RX_BURST is 32, so it will be 32 bytes. Then we cast it 
into a pointer for 4 byte values, and check the first 4 elements of that 
array

const uint32_t *split_fl32 = (uint32_t *)split_flags;
if (rxq->pkt_first_seg == NULL &&
		split_fl32[0] == 0 && split_fl32[1] == 0 &&
		split_fl32[2] == 0 && split_fl32[3] == 0)

So we only check the first half of this 32 byte array. But 
_recv_raw_pkts_vec() seems to use the whole array. Is this a bug or a 
feature? Or am I mistaken in the math somewhere?

Regards,

Zoltan Kiss