Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964777AbWJCOse (ORCPT ); Tue, 3 Oct 2006 10:48:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964785AbWJCOse (ORCPT ); Tue, 3 Oct 2006 10:48:34 -0400 Received: from smtp.osdl.org ([65.172.181.4]:29619 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S964777AbWJCOsd (ORCPT ); Tue, 3 Oct 2006 10:48:33 -0400 Date: Tue, 3 Oct 2006 07:48:22 -0700 (PDT) From: Linus Torvalds To: Andi Kleen cc: Randy Dunlap , akpm , Jesper Juhl , Linux Kernel Mailing List Subject: Re: [PATCH/RFC] Math-emu kills the kernel on Athlon64 X2 II -- it's terminally broken In-Reply-To: <200610031211.46168.ak@suse.de> Message-ID: References: <9a8748490609181518j2d12e4f0l2c55e755e40d38c2@mail.gmail.com> <20061002202426.aa3ecb4f.rdunlap@xenotime.net> <200610031211.46168.ak@suse.de> 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: 880 Lines: 30 On Tue, 3 Oct 2006, Andi Kleen wrote: > > Actually I looked at the code more closely. It looks like kernel math > emulation is much more broken. e.g. kernel_fpu_begin() is missing > code and lots of other paths in i387 that need to check HAVE_HWFP don't. No it's not. kernel_fpu_begin() has the _one_ test that matters: if (thread->status & TS_USEDFPU) { since if software emulation is on, nobody will ever have the TS_USEDFPU flag set. > Fixing it properly would be much more work. No. It's all fixed properly already. The bug is simply on the newer FXSR paths - marking the FPU emulation broken is just stupid. Linus - 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/