From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Tromey Subject: Re: linux-next: add utrace tree Date: Mon, 25 Jan 2010 14:05:54 -0700 Message-ID: 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> Reply-To: tromey@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: (Linus Torvalds's message of "Sat, 23 Jan 2010 21:04:56 -0800 (PST)") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: utrace-devel-bounces@redhat.com Errors-To: utrace-devel-bounces@redhat.com To: Linus Torvalds Cc: 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 List-Id: linux-next.vger.kernel.org >>>>> "Linus" == Linus Torvalds writes: Linus> No. There is absolutely _no_ reason to believe that gdb et al would ever Linus> delete the ptrace interfaces anyway. Yes, in GDB we approximately never delete anything. Nevertheless, if the Linux kernel were to present a new user-space API, and if it had an advantage over ptrace, then we would port GDB to use it. There are other platforms where, IIRC, we now use some /proc thing instead of ptrace. There are definitely things we would like from such an API. Here's a few I can think of immediately, there are probably others. * 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. * Support "displaced stepping" in the kernel; I think this would improve performance when debugging in non-stop mode. * Support some kind of breakpoint expression in the kernel; this would improve performance of conditional breakpoints. Perhaps the existing gdb agent expressions could be used. Tom