From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matteo Frigo Subject: Re: Cygwin bash's built-in test command crashes on Windows 2008 Server 64bit under KVM Date: Thu, 05 Feb 2009 20:28:34 -0500 Message-ID: <87bptgnykd.fsf@fftw.org> References: <40ddf2480901050654y268213d1jbf34f9d81d6faeb0@mail.gmail.com> <40ddf2480901050822q52a9c2b6x5d5d87d17dec4992@mail.gmail.com> <49788A80.2070403@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: kvm@vger.kernel.org Return-path: Received: from main.gmane.org ([80.91.229.2]:39586 "EHLO ciao.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757341AbZBFBkH (ORCPT ); Thu, 5 Feb 2009 20:40:07 -0500 Received: from root by ciao.gmane.org with local (Exim 4.43) id 1LVFhK-0000LD-Ev for kvm@vger.kernel.org; Fri, 06 Feb 2009 01:40:02 +0000 Received: from pool-96-237-78-200.bstnma.east.verizon.net ([96.237.78.200]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 06 Feb 2009 01:40:02 +0000 Received: from athena by pool-96-237-78-200.bstnma.east.verizon.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 06 Feb 2009 01:40:02 +0000 Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity writes: > - add a watchpoint to break when the value of gs:[0x30] changes It seems that the problem can be reproduced by compiling the following simple program using cygwin's gcc. The program crashes on w2k3-amd64 on kvm-83 on core2-duo, and it does not crash on the same w2k3-amd64 installation on kvm-83 on AMD Phenom. #include jmp_buf env; main() { if(setjmp(env)) return; longjmp(env, 1); } The problem seems to be in the instruction ``mov gs,ax'' (Intel syntax) in the longjmp() code. If I let the virtual machine execute the instruction, the program crashes. However, if I step over the instruction using the vs2008 debugger, the program completes without crashing. Thus, I think that this is the instruction that Avi is looking for, but I don't know how to proceed from here. Hope this helps. Cheers, Matteo Frigo