From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7854 invoked by alias); 31 Mar 2010 17:35:35 -0000 Received: (qmail 7846 invoked by uid 22791); 31 Mar 2010 17:35:34 -0000 X-SWARE-Spam-Status: No, hits=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from smtp-outbound-1.vmware.com (HELO smtp-outbound-1.vmware.com) (65.115.85.69) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 31 Mar 2010 17:35:31 +0000 Received: from mailhost4.vmware.com (mailhost4.vmware.com [10.16.67.124]) by smtp-outbound-1.vmware.com (Postfix) with ESMTP id EB1E27008; Wed, 31 Mar 2010 10:35:29 -0700 (PDT) Received: from msnyder-server.eng.vmware.com (promd-2s-dhcp138.eng.vmware.com [10.20.124.138]) by mailhost4.vmware.com (Postfix) with ESMTP id E4014C9A53; Wed, 31 Mar 2010 10:35:29 -0700 (PDT) Message-ID: <4BB387E1.3070702@vmware.com> Date: Wed, 31 Mar 2010 17:35:00 -0000 From: Michael Snyder User-Agent: Thunderbird 2.0.0.22 (X11/20090609) MIME-Version: 1.0 To: Pedro Alves CC: "gdb@sourceware.org" Subject: Re: Random gdbserver question (x86) References: <4BB28BF2.8080100@vmware.com> <201003310219.49529.pedro@codesourcery.com> In-Reply-To: <201003310219.49529.pedro@codesourcery.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2010-03/txt/msg00223.txt.bz2 Pedro Alves wrote: > On Wednesday 31 March 2010 00:40:34, Michael Snyder wrote: >> Question -- is gdbserver "multi-arch" to the extent that a 32-bit >> gdbserver (built with target = i386) can debug a 64-bit app? > > No, only the other way around. It's "multi-arch" to the extent > that a linux 64-bit gdbserver (built with target = x86-64) can > debug a 32-bit app. It used to only be, only 64x64 or 32x32 was > possible; with multi-arch, 64x32 was made possible. > >> I ask because linux-x86-low.c is full of ifdefs on the architecture. >> It looks like most of the 64-bit code won't be compiled if the >> build machine is 32-bit. > > Correct. And is that more-or-less true of gdb as well? I.e., if host/target is x86_64-linux, then gdb can debug both 32 and 64 bit apps, but if host/target is i386-linux, then gdb can only debug 32 bit apps? Actually, I phrase it as a question even though I am pretty sure it is true. My real question is "Why?". It seems to me that if we just included amd64-linux-nat.o and amd64-*-tdep.o in the build, then 32-bit gdb should be able to debug 64-bit native apps.