Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932262AbWHCFZX (ORCPT ); Thu, 3 Aug 2006 01:25:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932268AbWHCFZX (ORCPT ); Thu, 3 Aug 2006 01:25:23 -0400 Received: from cantor2.suse.de ([195.135.220.15]:6870 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S932262AbWHCFZX (ORCPT ); Thu, 3 Aug 2006 01:25:23 -0400 From: Andi Kleen To: Christoph Lameter Subject: Re: [patch 2/8] Implement always-locked bit ops, for memory shared with an SMP hypervisor. Date: Thu, 3 Aug 2006 07:25:13 +0200 User-Agent: KMail/1.9.3 Cc: virtualization@lists.osdl.org, Jeremy Fitzhardinge , akpm@osdl.org, xen-devel@lists.xensource.com, Chris Wright , Ian Pratt , linux-kernel@vger.kernel.org References: <20060803002510.634721860@xensource.com> <200608030649.11452.ak@suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200608030725.13713.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1573 Lines: 38 > As far as I can tell from this conversation there are special "Xen" > drivers that need this not the rest of the system. Yes, but in general when a driver that runs on multiple architectures (including IA64 btw) needs something architecture specific we usually add it to asm, not add ifdefs. > > > for those special xen drivers. > > > > Well there might be reasons someone else uses this in the future too. > > It's also not exactly Linux style - normally we try to add generic > > facilities. > > What possible use could there be to someone else? e.g. for other hypervisors or possibly for special hardware access (e.g. I could imagine it being used for some kind of cluster interconnect) I remember Alan was using a similar hack in his EDAC drivers because it was the only way to clear ECC errors. > The "atomic" ops lock/unlock crap exists only for i386 as far as I can > tell. As you said most architectures either always use atomic ops or > never. The lock/unlock atomic ops are i386 specific material that > better stay contained. Its arch specific and not generic. Well we have our share of weird hacks for IA64 too in generic code. Just adding a single line #include for a wrapper asm-generic surely isn't a undue burden for the other architectures, and it will save some mess in the Xen drivers. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/