From: Tom Herbert <tom@herbertland.com>
To: Edward Cree <ecree@solarflare.com>
Cc: netdev <netdev@vger.kernel.org>
Subject: Re: Checksum offload queries
Date: Tue, 8 Dec 2015 08:43:04 -0800 [thread overview]
Message-ID: <CALx6S37T8gA8ZNRTgWt5MBW8QLYa7ODnAoZm-=Xk5VNg_t3QSg@mail.gmail.com> (raw)
In-Reply-To: <5666FF46.6030702@solarflare.com>
On Tue, Dec 8, 2015 at 8:03 AM, Edward Cree <ecree@solarflare.com> wrote:
> On 07/12/15 17:29, Tom Herbert wrote:
>> On Mon, Dec 7, 2015 at 7:39 AM, Edward Cree <ecree@solarflare.com> wrote:
>>> 2) Transmit checksums.
>> It's analogous to CHECKSUM_COMPLETE, NETIF_F_HW_CSUM works for all
>> cases of checksum offload and any combination of protocol layering.
> ... until a protocol combination comes along that doesn't allow all but the innermost checksum to be 0. NETIF_F_HW_CSUM is limited to one checksum per packet.
So is NETIF_F_IP[V6]_CSUM, again the interface into the driver to
offload a checksum is csum_start, csum_offset. Only one checksum can
be offloaded at a time. We have no way to tell the driver that there
are two checksums in a packet to be offloaded. Good news is that we
probably don't need that. Extensible encapsulation protocols can
implement Remote Checksum Offload, and this is never an issue on the
receive side since CHECKSUM_COMPLETE can be used to validate and
arbitrary number of checksums.
Tom
next prev parent reply other threads:[~2015-12-08 16:43 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-07 15:39 Checksum offload queries Edward Cree
2015-12-07 17:29 ` Tom Herbert
2015-12-07 17:52 ` Tom Herbert
2015-12-08 16:03 ` Edward Cree
2015-12-08 16:43 ` Tom Herbert [this message]
2015-12-08 18:03 ` Edward Cree
2015-12-08 17:09 ` David Miller
2015-12-08 17:24 ` Edward Cree
2015-12-08 17:28 ` David Miller
2015-12-07 19:38 ` David Miller
2015-12-08 14:42 ` Edward Cree
2015-12-08 17:04 ` Tom Herbert
2015-12-09 1:56 ` Thomas Graf
2015-12-09 16:08 ` Tom Herbert
2015-12-09 22:29 ` Thomas Graf
2015-12-09 22:51 ` Tom Herbert
2015-12-09 23:13 ` Thomas Graf
2015-12-08 17:06 ` David Miller
2015-12-09 12:14 ` Edward Cree
2015-12-09 16:01 ` Tom Herbert
2015-12-09 17:28 ` Edward Cree
2015-12-09 17:31 ` David Laight
2015-12-09 18:00 ` Tom Herbert
2015-12-09 22:21 ` Thomas Graf
2015-12-09 22:42 ` Tom Herbert
2015-12-09 22:44 ` Thomas Graf
2015-12-10 15:49 ` Edward Cree
2015-12-10 16:26 ` Tom Herbert
2015-12-10 20:28 ` Edward Cree
2015-12-10 21:02 ` Rustad, Mark D
2015-12-14 15:11 ` [RFC PATCH net-next 0/2] Local checksum offload for VXLAN Edward Cree
2015-12-14 15:13 ` [PATCH 1/2] net: udp: local checksum offload for encapsulation Edward Cree
2015-12-14 17:16 ` Tom Herbert
2015-12-15 18:07 ` Edward Cree
2015-12-14 15:13 ` [PATCH 2/2] net: vxlan: enable local checksum offload on HW_CSUM devices Edward Cree
2015-12-11 23:50 ` Checksum offload queries Tom Herbert
2015-12-12 16:41 ` Sowmini Varadhan
2015-12-12 17:24 ` Tom Herbert
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