Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762862AbYBLRpN (ORCPT ); Tue, 12 Feb 2008 12:45:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758305AbYBLRo7 (ORCPT ); Tue, 12 Feb 2008 12:44:59 -0500 Received: from one.firstfloor.org ([213.235.205.2]:58324 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752315AbYBLRo7 (ORCPT ); Tue, 12 Feb 2008 12:44:59 -0500 Date: Tue, 12 Feb 2008 19:20:24 +0100 From: Andi Kleen To: Linus Torvalds Cc: Ingo Molnar , Andi Kleen , linux-kernel@vger.kernel.org, "Frank Ch. Eigler" , Roland McGrath , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton Subject: Re: [git pull] kgdb-light -v10 Message-ID: <20080212182024.GA4940@one.firstfloor.org> References: <20080211162141.GA31434@elte.hu> <20080211171039.GA20446@one.firstfloor.org> <20080211230335.GA16102@elte.hu> <20080212100327.GA30873@one.firstfloor.org> <20080212112747.GA1569@elte.hu> <20080212121903.GA419@one.firstfloor.org> <20080212123839.GA15360@elte.hu> <20080212135027.GA1343@one.firstfloor.org> <20080212152846.GC3078@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1003 Lines: 20 > - the kgdb commands should always act on the *current* CPU only > - add one command that says "switch over to CPU #n" which just releases > the current CPU and sends an IPI to that CPU #n (no timeouts, no > synchronous waiting, no nothing - it's like a "continue", but with a > "try to get the other CPU to stop" The problem I see here is that the kernel tends to get badly confused if one CPU just stops responding. At some point someone does an global IPI and that then hangs. You would need to hotunplug the CPU which is theoretically possible, but quite intrusive. Or maybe the "isolate CPUs in cpusets" frame work someone posted recently on l-k could be used. Still would probably have all kinds of tricky issues and races. -Andi -- 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/