Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757860AbYACTTR (ORCPT ); Thu, 3 Jan 2008 14:19:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756614AbYACTTA (ORCPT ); Thu, 3 Jan 2008 14:19:00 -0500 Received: from gw.goop.org ([64.81.55.164]:52555 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753040AbYACTS7 (ORCPT ); Thu, 3 Jan 2008 14:18:59 -0500 Message-ID: <477D34FB.6070601@goop.org> Date: Thu, 03 Jan 2008 11:18:19 -0800 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Chris Wright CC: Steven Rostedt , Chris Wright , Mathieu Desnoyers , Peter Zijlstra , Gregory Haskins , LKML , virtualization@lists.linux-foundation.org, Christoph Hellwig , Steven Rostedt , Arnaldo Carvalho de Melo , "William L. Irwin" , Ingo Molnar , Linus Torvalds , Andrew Morton Subject: Re: [RFC PATCH 01/11] Add basic support for gcc profiler instrumentation References: <20080103071609.478486470@goodmis.org> <20080103072226.776141236@goodmis.org> <20080103092104.GE10813@elte.hu> <20080103181651.GC3627@sequoia.sous-sol.org> In-Reply-To: <20080103181651.GC3627@sequoia.sous-sol.org> X-Enigmail-Version: 0.95.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1569 Lines: 35 Chris Wright wrote: > * Steven Rostedt (rostedt@goodmis.org) wrote: > >> Hmm, I know paravirt-ops had an issue with mcount in the RT tree. I can't >> remember the exact issues, but it did have something to do with the way >> parameters were passed in. >> >> Chris, do you remember what the issues were? >> > > Yes, paravirt ops have a well-specified calling convention (register > based). There was a cleanup that Andi did that caused the problem > because it removed all the "fastcall" annotations since -mregparm=3 > is now always on for i386. Since MCOUNT disables REGPARM the calling > convention changes (caller pushes to stack, callee expects register) > chaos ensues. I sent a patch to fix that quite some months back, but > it went stale and I neglected to update it. Would you like me to dig > it up refresh and resend? Ingo/Andrew have been accepting patches to systematically remove all the fastcall annotations from the kernel, so adding them back isn't going to help. Ingo and I discussed whether we need to reannotate paravirt.h (either with fastcall or something else indicating a register-only calling convention), specifically because of the -pg issue, but I think the conclusion was that whatever problem existed no longer does, and there's no incompatibility between -pg and regparm. J -- 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/