From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: skb_checksum_help Date: Tue, 25 Jan 2005 12:48:16 -0800 Message-ID: <41F6B090.6020602@candelatech.com> References: <20050124234515.GA31837@postel.suug.ch> <20050125000759.GA15883@gondor.apana.org.au> <20050124164049.3b939791.davem@davemloft.net> <20050125014538.GB31837@postel.suug.ch> <20050125014838.GA16637@gondor.apana.org.au> <20050125020118.GC31837@postel.suug.ch> <20050124180354.63ae600d.davem@davemloft.net> <20050125022431.GD31837@postel.suug.ch> <20050124194328.20a106de.davem@davemloft.net> <20050125143319.GF31837@postel.suug.ch> <20050125203607.GG31837@postel.suug.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , herbert@gondor.apana.org.au, david@davidcoulson.net, kaber@trash.net, netdev@oss.sgi.com Return-path: To: Thomas Graf In-Reply-To: <20050125203607.GG31837@postel.suug.ch> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Thomas Graf wrote: > * Thomas Graf <20050125143319.GF31837@postel.suug.ch> 2005-01-25 15:33 > >>* David S. Miller <20050124194328.20a106de.davem@davemloft.net> 2005-01-24 19:43 >> >>>On Tue, 25 Jan 2005 03:24:31 +0100 >>>Thomas Graf wrote: >>> >>> >>>>This of course explains it, didn't think of that. I thought it would >>>>inherit the checksumming features. >>> >>>It should, but only in very limited cases. >>> >>>Because it is very chip dependant whether this works or not in >>>any case, we should probably create a special features flag for >>>this. Something like NETIF_F_VLAN_INHERIT_FEATURES. >> >>Can't we just use NETIF_F_HW_VLAN_TX for this and inherit >>NETIF_F_HW_CSUM | NETIF_F_IP_CSUM if it is set? I don't have any >>specs at hand though. > > > Vlan devices don't inherit any features at the moment but it would make > sense to do so. > > NETIF_F_SG|NETIF_F_TSO: > The normal vlan code seems to handle pskbs correctly, we don't gain > that much though. The big gain would be in the driver specific accel > code. I assume that the driver specific accel code is aware of > pskbs if the card can handle it but I haven't checked this yet. > > NETIF_F_NO_CSUM: > Avoid checksumming for vlan devices on loopback interfaces. > > NETIF_F_HIGHDMA|NETIF_F_FRAGLIST: > Didn't find a reason why this would cause problems. > > NETIF_F_LLTX: > vlan code accesses statistic counters so I think we can't > inherit. It might be worth to make it clean though. > > NETIF_F_IP_CSUM|NETIF_F_HW_CSUM: > Assuming that the vlan accel code can always do the checksumming > if the card can do it. I am leery of assuming these things for all drivers and all chipsets. Maybe the driver itself could tell vlan code what sorts of flags it can set? That takes the guess-work out, and each driver can add the features support as it is verified to work. If any particular hacks need to be used (ie, maybe chipset foo.rev-1a can't handle one particular thing), then the VLAN code doesn't have to care. new_dev->features = real_dev->vlan_features; -- Ben Greear Candela Technologies Inc http://www.candelatech.com