From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: PROBLEM: compilation issue, inline assembly arch/x86/kvm/emulate.c fails at -O0 Date: Wed, 14 Nov 2012 16:14:11 -0800 Message-ID: <50A433D3.6090301@zytor.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: "tglx@linutronix.de" , "mingo@redhat.com" , "avi@redhat.com" , "x86@kernel.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" To: "Blower, Melanie" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 11/14/2012 11:45 AM, Blower, Melanie wrote: > [1.] gcc -O0 assembly arch/x86/kvm/emulate.c gets compilation failure -- incorrect register restrictions > [2.] Full description of the problem/report: > I'm trying to compile this file at -O0, but gcc chokes in register allocation at the inline assembly. > > In the ordinary Linux build, this file compiles with gcc at -O2, without compilation errors. Compiling with -O0 is not really expected to work (although -O1 *is*), although what you are reporting is an actual bug ("+a" : "a" should either be "+a" or "=a" : "a"). -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.