From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932137AbWFUNxF (ORCPT ); Wed, 21 Jun 2006 09:53:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932147AbWFUNxE (ORCPT ); Wed, 21 Jun 2006 09:53:04 -0400 Received: from zeus1.kernel.org ([204.152.191.4]:4255 "EHLO zeus1.kernel.org") by vger.kernel.org with ESMTP id S932137AbWFUNxD (ORCPT ); Wed, 21 Jun 2006 09:53:03 -0400 Date: Wed, 21 Jun 2006 09:49:18 -0400 From: Daniel Jacobowitz To: "Frank Ch. Eigler" Cc: Roland McGrath , Chuck Ebbert <76306.1226@compuserve.com>, "Charles P. Wright" , Renzo Davoli , linux-kernel , Blaisorblade , Jeff Dike Subject: Re: [RFC PATCH 0/4] utrace: new modular infrastructure for user debug/tracing Message-ID: <20060621134918.GA1361@nevyn.them.org> Mail-Followup-To: "Frank Ch. Eigler" , Roland McGrath , Chuck Ebbert <76306.1226@compuserve.com>, "Charles P. Wright" , Renzo Davoli , linux-kernel , Blaisorblade , Jeff Dike References: <200606151900_MC3-1-C293-BD30@compuserve.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.11+cvs20060403 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 16, 2006 at 10:42:00AM -0400, Frank Ch. Eigler wrote: > Indeed, I like what I see (at least those parts I understand) in > roland's utrace code. One missed opportunity bit appears to be any > new support for something like per-thread breakpoints. > > If I correctly understand how gdb etc. work, a hit breakpoint involves > stoppage of all other threads of a process, then the breakpoint > instruction is replaced by the original one, then the thread is > single-stepped, then the breakpoint is put back, then finally all > threads are resumed. Could utrace API provide short-lived per-thread > page copies to execute the single-stepped original instruction out of, > and avoid stopping & resuming all other threads? FYI: I talked with Roland about this a while ago, and got the impression that he was interested in implementing it, but wanted to get utrace going first. It doesn't really relate to utrace; but it would need a new interface however it was implemented. GDB really does crave this feature. -- Daniel Jacobowitz CodeSourcery