Subject: Re: tap/bridge: Dropping NETIF_F_GSO/NETIF_F_SG

From: "Michael S. Tsirkin" <[email-masked]>
Date: Mon, 16 May 2011 10:32:10 +0300

On Thu, May 05, 2011 at 08:05:06PM +1000, Herbert Xu wrote:
> On Thu, May 05, 2011 at 05:34:43PM +0800, Shan Wei wrote:
> >
> > TUN_F_TSO4, TUN_F_TSO6, TUN_F_TSO_ECN, TUN_F_UFO these features are 
> > depend on NETIF_F_SG. If NETIF_F_SG is not set, these features are not be
> > enabled and  warnings are printed in netdev_fix_features().
> 
> No, when the user turns off checksum offload everything should
> be turned off as well.  However, when it's turned on, we shouldn't
> enable everything automatically.
> 
> Cheers,

So how is NETIF_F_SG supposed to be enabled then?

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.

> -- 
> Email: Herbert Xu <[email-masked]>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to [email-masked]
> More majordomo info at  http://vger.kernel.org/majordomo-info.html