From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758748AbZBSMKr (ORCPT ); Thu, 19 Feb 2009 07:10:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754503AbZBSMKh (ORCPT ); Thu, 19 Feb 2009 07:10:37 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:36839 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753916AbZBSMKh (ORCPT ); Thu, 19 Feb 2009 07:10:37 -0500 Date: Thu, 19 Feb 2009 13:10:27 +0100 From: Ingo Molnar To: Petr Tesarik , "H. Peter Anvin" Cc: Jeremy Fitzhardinge , LKML Subject: Re: Definition of BUG on x86 Message-ID: <20090219121027.GB1703@elte.hu> References: <1234975856.15053.16.camel@nathan.suse.cz> <499C4786.5010504@goop.org> <1235043648.15053.35.camel@nathan.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1235043648.15053.35.camel@nathan.suse.cz> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Petr Tesarik wrote: > So, the only method I could invent was using gas macros. It > works but is quite ugly, because it relies on the actual > assembler instruction which is generated by the compiler. Now, > AFAIK gcc has always translated "for(;;)" into a jump to self, > and that with any conceivable compiler options, but I don't > know anything about Intel cc. > +static inline __noreturn void discarded_jmp(void) > +{ > + asm volatile(".macro jmp target\n" > + "\t.purgem jmp\n" > + ".endm\n"); > + for (;;) ; > +} hm, that's very fragile. Why not just: static inline __noreturn void x86_u2d(void) { asm volatile("u2d\n"); } If GCC emits a bogus warning about _that_, then it's a bug in the compiler that should be fixed. Ingo