From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: linux-next: add utrace tree Date: Tue, 26 Jan 2010 18:33:26 +0100 Message-ID: <877hr4g49l.fsf@basil.nowhere.org> References: <20100121013822.28781960.sfr@canb.auug.org.au> <20100122005147.GD22003@redhat.com> <20100121170541.7425ff10.akpm@linux-foundation.org> <20100122182827.GA13185@redhat.com> <20100122200129.GG22003@redhat.com> <20100122221348.GA4263@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from one.firstfloor.org ([213.235.205.2]:53296 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753858Ab0AZRd2 (ORCPT ); Tue, 26 Jan 2010 12:33:28 -0500 In-Reply-To: (Tom Tromey's message of "Mon, 25 Jan 2010 14:05:54 -0700") Sender: linux-next-owner@vger.kernel.org List-ID: To: tromey@redhat.com Cc: Linus Torvalds , Stephen Rothwell , Kyle Moffett , Peter Zijlstra , Peter Zijlstra , Fr??d??ric Weisbecker , Oleg Nesterov , Steven Rostedt , LKML , Arnaldo Carvalho de Melo , "Frank Ch. Eigler" , linux-next@vger.kernel.org, "H. Peter Anvin" , utrace-devel@redhat.com, Thomas Gleixner Tom Tromey writes: > * Use an fd, not SIGCHLD+wait, to report inferior state changes to gdb. > Internally we're already using a self-pipe to integrate this into > gdb's main loop. Relatedly, don't mess with the inferior's parentage. How would having a kernel based solution be better over your user space simulation? BTW there's the new signalfd() system call that might do it (haven't checked if it works for SIGCHLD) > * Support "displaced stepping" in the kernel; I think this would improve > performance when debugging in non-stop mode. Not sure what "displaced stepping" is exactly, but it sounds like the branch tracing extensions that got added a few releases ago? On modern Intel chips they give you a branch buffer in memory. -Andi -- ak@linux.intel.com -- Speaking for myself only.