From: Christoph Hellwig Subject: Re: [PATCH 1/2] remove CONFIG_HAVE_ARCH_DEV_ALLOC_SKB Date: Wed, 26 Jul 2006 09:58:25 +0200 Message-ID: <20060726075825.GB28526@lst.de> References: <20060707091008.GB2543@lst.de> <20060724.153044.10246226.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , hch@lst.de, netdev@vger.kernel.org Return-path: Received: from verein.lst.de ([213.95.11.210]:59802 "EHLO mail.lst.de") by vger.kernel.org with ESMTP id S964790AbWGZH7p (ORCPT ); Wed, 26 Jul 2006 03:59:45 -0400 To: Roland Dreier Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, Jul 24, 2006 at 03:44:15PM -0700, Roland Dreier wrote: > > skbuff.h has an #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB to allow > > architectures to reimplement __dev_alloc_skb. It's not set on any > > architecture and now that we have an architecture-overrideable > > NET_SKB_PAD there is not point at all to have one either. > > I missed this when hch first posted it, sorry. > > But my impression was that the intent of the config option was to let > Xen hook __dev_alloc_skb() to allocate special receive skbs to handle > their page-flipping virtual network device. Which goes beyond > NET_SKB_PAD. > > So the real question is about Xen hooks I guess -- and given where the > rest of Xen is, it probably does make sense to go ahead and strip this > out. If xen wants to use something else then dev_alloc_skb in their virtual network driver that's totall fine. No need to override the definiton of dev_alloc_skb for that, though. They can add their own xen_alloc_skb or opencode the operation they want for it. Note that overriding dev_alloc_skb is not just utterly pointless but would even be harmfull in the case they'd finally add pci support for non-dom0 domains and used normaly NIC drivers in there.