Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937941AbWLGBxJ (ORCPT ); Wed, 6 Dec 2006 20:53:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S937946AbWLGBxJ (ORCPT ); Wed, 6 Dec 2006 20:53:09 -0500 Received: from scrub.xs4all.nl ([194.109.195.176]:48600 "EHLO scrub.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S937941AbWLGBxF (ORCPT ); Wed, 6 Dec 2006 20:53:05 -0500 Date: Thu, 7 Dec 2006 02:52:51 +0100 (CET) From: Roman Zippel X-X-Sender: roman@scrub.home To: Linus Torvalds cc: Matthew Wilcox , Christoph Lameter , David Howells , Andrew Morton , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it In-Reply-To: Message-ID: References: <20061206164314.19870.33519.stgit@warthog.cambridge.redhat.com> <20061206190025.GC9959@flint.arm.linux.org.uk> <20061206195820.GA15281@flint.arm.linux.org.uk> <20061206213626.GE3013@parisc-linux.org> <20061206220532.GF3013@parisc-linux.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1254 Lines: 29 Hi, On Wed, 6 Dec 2006, Linus Torvalds wrote: > > m68060 produces a trap for unaligned atomic access, unfortunately standard > > alignment is smaller than this. > > Umm. on 68060, since it's 32-bit, you'd only have the 32-bit case. Are you > saying that you can't do a 32-bit atomic access at any 32-bit aligned > boundary? Or are you saying that gcc aligns normal 32-bit entities at > 16-bit alignment? Neither of those sound very likely. The latter. And yes, I'm starting to hate it too, especially after I've seen all the weird bugs this causes in userspace, which then only trigger on m68k. I'm thinking of changing it when switching to proper TLS support, but it's not there yet. BTW there is another reason I actually like the atomic type - documentation. It makes it more clear that this intended to be used as atomic value, so an unhealthy mixture of different accesses is less likely and if they pile up at some place it's a good indicator to maybe switch back to spinlocks. bye, Roman - 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/