From mboxrd@z Thu Jan 1 00:00:00 1970 From: Willy Tarreau Subject: Re: [ACPI] Re: Linux 2.4.26-rc1 (cmpxchg vs 80386 build) Date: Tue, 30 Mar 2004 16:22:15 +0200 Sender: linux-kernel-owner@vger.kernel.org Message-ID: <20040330142215.GA21931@alpha.home.local> References: <1080535754.16221.188.camel@dhcppc4> <20040329052238.GD1276@alpha.home.local> <1080598062.983.3.camel@dhcppc4> <1080651370.25228.1.camel@dhcp23.swansea.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: To: "Richard B. Johnson" Cc: Alan Cox , Len Brown , Arkadiusz Miskiewicz , Marcelo Tosatti , Linux Kernel Mailing List , ACPI Developers List-Id: linux-acpi@vger.kernel.org On Tue, Mar 30, 2004 at 08:15:46AM -0500, Richard B. Johnson wrote: > On Tue, 30 Mar 2004, Alan Cox wrote: > > > On Llu, 2004-03-29 at 23:07, Len Brown wrote: > > > Linux uses this locking mechanism to coordinate shared access > > > to hardware registers with embedded controllers, > > > which is true also on uniprocessors too. > > > > If the ACPI layer simply refuses to run on a CPU without cmpxchg > > then I can't see there being a problem, there don't appear to be > > any 386 processors with ACPI > > > > Yep, but to get to use cmpxchg, you need to compile as a '486 or > higher. This breaks i386. OK, so why not compile the cmpxchg instruction even on i386 targets to let generic kernels stay compatible with everything, but disable ACPI at boot if the processor does not feature cmpxchg ? This could be helpful for boot/install kernels which try to support a wide range of platforms, and may need ACPI to correctly enable interrupts on others. Cheers, Willy