From: "Michael S. Tsirkin" <mst@redhat.com>
To: Herbert Xu <herbert@gondor.hengli.com.au>
Cc: "Shan Wei" <shanwei@cn.fujitsu.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
netdev@vger.kernel.org,
"Ben Hutchings" <bhutchings@solarflare.com>
Subject: Re: tap/bridge: Dropping NETIF_F_GSO/NETIF_F_SG
Date: Mon, 16 May 2011 11:18:41 +0300 [thread overview]
Message-ID: <20110516081841.GA8073@redhat.com> (raw)
In-Reply-To: <20110516080702.GA1857@gondor.apana.org.au>
On Mon, May 16, 2011 at 06:07:02PM +1000, Herbert Xu wrote:
> On Mon, May 16, 2011 at 10:32:10AM +0300, Michael S. Tsirkin wrote:
> >
> > So how is NETIF_F_SG supposed to be enabled then?
>
> It should either be enabled at device creation time, or whatever
> user-space entity managing the device creation should enable it
> along with checksumming and anything else applicable.
There's no interface for userspace to enable it: userspace
only has an ioctl to enable/disable checksum offloading.
SG is an implementation detail.
> > In upstream kernels userspace can disable checksum offloading then
> > re-enable and get SG set back. userspace came to depend on this
> > behaviour so I think changing this is a regression.
>
> Can you point me to the relevant code in the upstream kernel?
> I'm not aware of any automatic SG enabling for network devices
> in general when you enable checksum offloading.
>
> Cheers,
I think what happens _SG is enabled at device creation time and
then upstream just keeps it on always, even when user clears
CSUM. With net-next code changed so that _SG gets cleared when CSUM
'gets cleared. But then it does not get reenabled when CSUM
gets reenabled.
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2011-05-16 8:18 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-04 18:18 tap/bridge: Dropping NETIF_F_GSO/NETIF_F_SG Michael S. Tsirkin
2011-05-04 22:34 ` Herbert Xu
2011-05-04 23:28 ` Michał Mirosław
2011-05-05 0:19 ` Herbert Xu
2011-05-05 8:44 ` Michael S. Tsirkin
2011-05-05 9:34 ` Shan Wei
2011-05-05 10:05 ` Herbert Xu
2011-05-16 7:32 ` Michael S. Tsirkin
2011-05-16 8:07 ` Herbert Xu
2011-05-16 8:18 ` Michael S. Tsirkin [this message]
2011-05-16 9:38 ` Herbert Xu
2011-05-16 9:48 ` Michael S. Tsirkin
2011-05-16 10:43 ` Herbert Xu
2011-05-16 11:21 ` Michael S. Tsirkin
2011-05-16 12:18 ` Herbert Xu
2011-05-16 12:24 ` Michał Mirosław
2011-05-16 22:46 ` Herbert Xu
2011-05-16 23:06 ` David Miller
2011-05-16 23:45 ` Herbert Xu
2011-05-17 5:18 ` Michael S. Tsirkin
2011-05-17 5:24 ` Herbert Xu
2011-05-17 5:48 ` Michael S. Tsirkin
2011-05-17 6:25 ` Herbert Xu
2011-05-17 8:08 ` Michał Mirosław
2011-05-17 8:15 ` Michał Mirosław
2011-05-17 8:19 ` [PATCH] net: tuntap: Fix tun_net_fix_features() Michał Mirosław
2011-05-17 14:29 ` Michael S. Tsirkin
2011-05-17 14:46 ` Michał Mirosław
2011-05-17 14:54 ` Michael S. Tsirkin
2011-05-17 15:00 ` Michał Mirosław
2011-05-17 15:11 ` Michael S. Tsirkin
2011-06-01 9:25 ` Michael S. Tsirkin
2011-06-20 19:14 ` [RESENT PATCH] " Michał Mirosław
2011-06-20 19:25 ` Ben Hutchings
2011-06-20 19:44 ` Michał Mirosław
2011-05-16 10:53 ` tap/bridge: Dropping NETIF_F_GSO/NETIF_F_SG Michał Mirosław
2011-05-16 8:28 ` Michael S. Tsirkin
2011-05-05 15:26 ` Michał Mirosław
2011-05-14 6:54 ` Shan Wei
2011-05-16 7:28 ` Michael S. Tsirkin
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