From: Cliff Burdick <shaklee3@gmail.com>
To: David Aldrich <david.aldrich.ntml@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 07:59:00 -0700 [thread overview]
Message-ID: <CA+Gp1naGYOriSbEKFt=FA6p0tmr=8LbBH3pjAD_SURsfqwCzZQ@mail.gmail.com> (raw)
In-Reply-To: <CAJK_iej-DmLnFW5D7OZ7Fjw3a9_3DuBM8v=zeibht5MFwnKHdg@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. 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 14:59 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 [this message]
2020-07-01 15:06 ` David Aldrich
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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