From: David Aldrich <david.aldrich.ntml@gmail.com>
To: Cliff Burdick <shaklee3@gmail.com>
Cc: users <users@dpdk.org>
Subject: Re: [dpdk-users] Why is udp packet, sent by dpdk, received with zero'd payload?
Date: Wed, 1 Jul 2020 16:06:44 +0100 [thread overview]
Message-ID: <CAJK_iegMP3fLAaDzvDQrzz2U0+ARegj+i4HcWzndgqLOyBBFow@mail.gmail.com> (raw)
In-Reply-To: <CA+Gp1naGYOriSbEKFt=FA6p0tmr=8LbBH3pjAD_SURsfqwCzZQ@mail.gmail.com>
>If you look at the code for rte_pktmbuf_prepend it appears to be just
>incrementing data_len and pkt_len by the same amount.
I'm sorry, but I don't understand. My calls to rte_pktmbuf_prepend are:
p_udp_hdr = (struct udp_hdr*)rte_pktmbuf_prepend(ptMbuf,
(uint16_t)sizeof(struct udp_hdr));
p_ip_hdr = (struct ipv4_hdr*)rte_pktmbuf_prepend(ptMbuf,
(uint16_t)sizeof(struct ipv4_hdr));
are you saying that those calls are wrong? When you say 'if you look
at the code' are you referring to this code?
(I thought it best that I should ask for clarification rather than guess).
Thanks
On Wed, Jul 1, 2020 at 3:59 PM Cliff Burdick <shaklee3@gmail.com> wrote:
> If you look at the code for rte_pktmbuf_prepend it appears to be just
> incrementing data_len and pkt_len by the same amount. My guess is that
> those fields were not set to the correct values before you called
> rte_pktmbuf_prepend().
>
> On Wed, Jul 1, 2020 at 6:41 AM David Aldrich <david.aldrich.ntml@gmail.com>
> wrote:
>
>> I think this is where my lack of understanding is my problem. Looking at
>> the mbuf dump:
>>
>> dump mbuf at 0x53e4e92c0, iova=73e4e9340, buf_len=2176
>> pkt_len=57, ol_flags=c0000000000000, nb_segs=2, in_port=65535
>> segment at 0x53e4e92c0, data=0x53e4e9396, data_len=42
>> Dump data at [0x53e4e9396], len=42
>> 00000000: 94 40 C9 1F C4 DB 94 40 C9 1E 13 7D 08 00 45 B8 | .@.....@...}..E.
>> 00000010: 00 2B 00 00 00 00 40 11 F5 E8 C0 A8 01 69 C0 A8 | .+....@......i..
>> 00000020: 01 68 0B B9 0B B8 00 17 64 2D | | | | | | | .h......d-
>> segment at 0x53e146e40, data=0x53e4fbbc0, data_len=15
>> Dump data at [0x53e4fbbc0], len=15
>> 00000000: 48 65 6C 6C 6F 20 66 72 6F 6D 20 64 70 64 6B | | Hello from dpdk
>>
>> It consists of two parts (segments?), of lengths 42 and 15. This makes sense to me as I first
>> put the payload in the mbuf (15 bytes) and then added the Ethernet and L3 headers (42 bytes) by calling rte_pktmbuf_prepend().
>>
>> I guess only the first segment is getting transmitted?
>>
>>
>> On Wed, Jul 1, 2020 at 1:57 PM Cliff Burdick <shaklee3@gmail.com> wrote:
>>
>>> Are you setting data_len and packet_len in the mbuf before sending?
>>>
>>>
>>> On Wed, Jul 1, 2020, 03:23 David Aldrich <david.aldrich.ntml@gmail.com>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> I have a problem transmitting udp packets with dpdk-stable-18.11.8. I
>>>> have
>>>> posted a question about it on stackoverflow:
>>>>
>>>>
>>>> https://stackoverflow.com/questions/62674596/why-is-udp-packet-sent-by-dpdk-received-with-zerod-payload
>>>>
>>>> I would be grateful for any comments either there or in this group
>>>> please.
>>>>
>>>> Best regards
>>>>
>>>> David
>>>>
>>>
next prev parent reply other threads:[~2020-07-01 15:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 10:23 David Aldrich
2020-07-01 12:57 ` Cliff Burdick
2020-07-01 13:04 ` David Aldrich
2020-07-01 13:08 ` Cliff Burdick
2020-07-01 13:40 ` David Aldrich
2020-07-01 14:59 ` Cliff Burdick
2020-07-01 15:06 ` David Aldrich [this message]
2020-07-01 15:38 ` Cliff Burdick
2020-07-01 15:56 ` Matt Laswell
2020-07-01 16:48 ` David Aldrich
2020-07-01 17:57 ` Cliff Burdick
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