From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: skb_checksum_help Date: Tue, 25 Jan 2005 14:14:14 -0800 Message-ID: <41F6C4B6.20800@candelatech.com> References: <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> <41F6B090.6020602@candelatech.com> <20050125211524.GH31837@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: <20050125211524.GH31837@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: > * Ben Greear <41F6B090.6020602@candelatech.com> 2005-01-25 12:48 > >>Thomas Graf wrote: >> >>>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; >> > > * David S. Miller <20050125125019.5ca32de1.davem@davemloft.net> 2005-01-25 12:50 > >>I bet there are cards that don't have VLAN hw assist yet >>can properly checksum such packets. One example I am counting >>on to fit this property is the 3c59x. >> >>This is why I'm suggesting some kind of inheritance indication >>explicitly from the real_dev driver. Perhaps even something >>like: >> >> unsigned int vlan_inherited_features; >> >>in the netdev struct. > > > I thought about this too and actually implemented it but it means to > change all relevant drivers and the only feature that might be > driver specific is checksumming, given I didn't make any mistakes > while checking the drivers for pskb compatibility. Therefore I tried > to avoid it but it seems we can't get around it. > > Any objections in inheriting SG|NO_CSUM|HIGH_DMA|FRAGLIST|TSO by > default or leave it to the driver as well? I'd leave everything to the driver. Once we add the new flags field (vlan_inherited_features), then it's trivial to just set the flags and not have to worry about automatic inheritance. -- Ben Greear Candela Technologies Inc http://www.candelatech.com