From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965077AbVHPDHi (ORCPT ); Mon, 15 Aug 2005 23:07:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965078AbVHPDHi (ORCPT ); Mon, 15 Aug 2005 23:07:38 -0400 Received: from quark.didntduck.org ([69.55.226.66]:35284 "EHLO quark.didntduck.org") by vger.kernel.org with ESMTP id S965077AbVHPDHh (ORCPT ); Mon, 15 Aug 2005 23:07:37 -0400 Message-ID: <43015894.1090307@didntduck.org> Date: Mon, 15 Aug 2005 23:08:04 -0400 From: Brian Gerst User-Agent: Mozilla Thunderbird 1.0.6-3 (X11/20050806) X-Accept-Language: en-us, en MIME-Version: 1.0 To: zach@vmware.com CC: akpm@osdl.org, chrisw@osdl.org, linux-kernel@vger.kernel.org, virtualization@lists.osdl.org Subject: Re: [PATCH 0/6] i386 virtualization patches, Set 3 References: <200508152258.j7FMw9p8005295@zach-dev.vmware.com> In-Reply-To: <200508152258.j7FMw9p8005295@zach-dev.vmware.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org zach@vmware.com wrote: > This round attempts to conclude all of the LDT related cleanup with some > finally nice looking LDT code, fixes for the UML build, a bugfix for > really rather nasty kprobes problems, and the basic framework for an LDT > test suite. It is really rather unfortunate that this code is so > difficult to test, even with DOSemu and Wine, there are still very nasty > corner cases here - anyone want an iret to 16-bit stack test?. > > I was going to attempt to clean up the math-emu code to make it use the > nice new segment and descriptor table accessors, but it quickly became > apparent that this would be a long, tedious, error prone process that > would eventually result in the death of a large section of my brain. > In addition, it is not very fun to test this on the actual hardware it > is designed to run on (although I did manage to track down a 386 with > detachable i387 coprocessor, the owner is not sure it still boots). > Someday it would be nice to have an audit of this code; it appears to > be riddled with bugs relating to segmentation, for example it assumes > LDT segments on overrides, does not use the mm->context semaphore to > protect LDT access, and generally looks scarily out of date in both > function and appearance. If you really want to test the math emu code, you can hack check_x87 in head.S to always leave the fpu disabled. Then you can test it on any cpu, not just a 386. -- Brian Gerst