From: Jaeden Amero <jaeden.amero@ni.com>
To: David Miller <davem@davemloft.net>
Cc: nicolas.ferre@atmel.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, jeff.westfahl@ni.com,
mihai.neagu@ni.com
Subject: Re: [PATCH RFC] net/macb: Fix UDPv4 checksum offload
Date: Tue, 28 Apr 2015 15:36:54 -0500 [thread overview]
Message-ID: <553FEF66.7010503@ni.com> (raw)
In-Reply-To: <20150427.224713.291017556251723132.davem@davemloft.net>
On 04/27/2015 09:47 PM, David Miller wrote:
> From: Jaeden Amero <jaeden.amero@ni.com>
> Date: Mon, 27 Apr 2015 17:43:30 -0500
>
> A UDP checksum of zero, means "checksum not computed". And your
> device isn't computing the checksum at all, but rather is leaving it
> at zero.
The "zero" checksum is not what gets sent over the wire. Independent of
the value of the checksum field, hardware generates a correct checksum
for payloads of 3 or more bytes. The bug is that hardware generates an
incorrect checksum for payloads of 2 or less bytes, unless the checksum
field is zeroed.
> You need to handle this properly by computing the checksum in
> software and then setting the TX descriptor bits such that the
> chip leaves the checksum field alone.
Unfortunately, the Cadence MACB doesn't support the enabling or
disabling of checksum generation per descriptor.
next prev parent reply other threads:[~2015-04-28 20:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-27 22:43 [PATCH RFC] net/macb: Fix UDPv4 checksum offload Jaeden Amero
2015-04-28 2:47 ` David Miller
2015-04-28 20:36 ` Jaeden Amero [this message]
2015-04-28 20:47 ` David Miller
2015-04-29 10:15 ` One Thousand Gnomes
2015-04-29 16:03 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=553FEF66.7010503@ni.com \
--to=jaeden.amero@ni.com \
--cc=davem@davemloft.net \
--cc=jeff.westfahl@ni.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mihai.neagu@ni.com \
--cc=netdev@vger.kernel.org \
--cc=nicolas.ferre@atmel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).