Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763516AbZAPJBU (ORCPT ); Fri, 16 Jan 2009 04:01:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761556AbZAPJAI (ORCPT ); Fri, 16 Jan 2009 04:00:08 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:47028 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761491AbZAPJAE (ORCPT ); Fri, 16 Jan 2009 04:00:04 -0500 Date: Fri, 16 Jan 2009 10:00:02 +0100 From: Pavel Machek To: Ingo Molnar Cc: "Maciej W. Rozycki" , Alan Cox , Jan-Benedict Glaw , Peter Zijlstra , Jiri Kosina , Adam Osuchowski , linux-kernel@vger.kernel.org, Nick Piggin , Thomas Gleixner , "H. Peter Anvin" Subject: Re: Is 386 processor still supported? Message-ID: <20090116090002.GD4795@atrey.karlin.mff.cuni.cz> References: <1231424833.11687.452.camel@twins> <20090108150448.2393aeb0@lxorguk.ukuu.org.uk> <20090108151046.GK18120@elte.hu> <20090115123614.GR11087@lug-owl.de> <20090115133252.28c36adb@lxorguk.ukuu.org.uk> <20090115141734.GA15732@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090115141734.GA15732@elte.hu> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1607 Lines: 36 > > * Maciej W. Rozycki wrote: > > > On Thu, 15 Jan 2009, Alan Cox wrote: > > > > > > UP emulation of CMPXCHG and XADD for userland should be rather trivial, > > > > so why not include it like with LL/SC for MIPS? > > > > > > Why not just ship an additional libc with the right options ? > > > > Does not work for MIPS as glibc has no equivalent code for pre-LL/SC > > CPUs and LL/SC is always used. For the i386 the situation seems worse > > yet as for pre-i486 CPUs a generic C implementation of > > compare-and-exchange is used guaranteeing silent thread unsafety. :( > > > > IMO, a kernel emulation of CMPXCHG and XADD (both are used by > > sysdeps/i386/i486/bits/atomic.h in glibc) with an optional LOCK prefix, > > guaranteeing UP atomicity would be a cheap way to provide long-term i386 > > userland support with little burden for both Linux and respective user > > software maintainers. Certainly it adds some bloat to the kernel, but I > > think it is not an option that should be outright dismissed without > > consideration. > > patches are welcome ... Hehe, I guess the only long-term solution is to get shiny old 386 as a part of Ingo's test farm ;-). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/