From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932508AbWFHAbu (ORCPT ); Wed, 7 Jun 2006 20:31:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932510AbWFHAbu (ORCPT ); Wed, 7 Jun 2006 20:31:50 -0400 Received: from gate.crashing.org ([63.228.1.57]:20370 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S932508AbWFHAbu (ORCPT ); Wed, 7 Jun 2006 20:31:50 -0400 Subject: Re: mutex vs. local irqs (Was: 2.6.18 -mm merge plans) From: Benjamin Herrenschmidt To: Ingo Molnar Cc: Andrew Morton , linux-kernel@vger.kernel.org, paulus@samba.org In-Reply-To: <20060607132155.GB14425@elte.hu> References: <20060604135011.decdc7c9.akpm@osdl.org> <1149652378.27572.109.camel@localhost.localdomain> <20060606212930.364b43fa.akpm@osdl.org> <1149656647.27572.128.camel@localhost.localdomain> <20060606222942.43ed6437.akpm@osdl.org> <1149662671.27572.158.camel@localhost.localdomain> <20060607132155.GB14425@elte.hu> Content-Type: text/plain Date: Thu, 08 Jun 2006 10:31:24 +1000 Message-Id: <1149726685.23790.8.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > a better solution would be to install boot-time IRQ vectors that just do > nothing but return. They dont mask, they dont ACK nor EOI - they just > return. The only thing that could break this is a screaming interrupt, > and even that one probably just slows things down a tiny bit until we > get so far in the init sequence to set up the PIC. Changing vectors on the fly is hard on some platforms.... We could change our toplevel ppc_md.get_irq() on powerpc, but we still to do something about decrementer interrupts. A screaming level interrupt will lockup the machine at least on some platforms. The problem with all those approaches is that they require changes to all archs interrupt handling to make the situation safe vs. mutexes... I still don't think where is the suckage in just not hard-enabling in the mutex debug code... Ben.