From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 58462 invoked by alias); 27 Apr 2015 20:17:58 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 58451 invoked by uid 89); 27 Apr 2015 20:17:58 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.7 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_SOFTFAIL autolearn=no version=3.3.2 X-HELO: bigwig.baldwin.cx Received: from bigwig.baldwin.cx (HELO bigwig.baldwin.cx) (96.47.65.170) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (CAMELLIA256-SHA encrypted) ESMTPS; Mon, 27 Apr 2015 20:17:57 +0000 Received: from ralph.baldwin.cx (pool-173-54-116-245.nwrknj.fios.verizon.net [173.54.116.245]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 1F41CB94A; Mon, 27 Apr 2015 16:17:55 -0400 (EDT) From: John Baldwin To: gdb-patches@sourceware.org Cc: Mark Kettenis , palves@redhat.com Subject: Re: [PATCH 1/3] Add fbsd_nat_add_target. Date: Mon, 27 Apr 2015 20:36:00 -0000 Message-ID: <4869684.VuRe0HgzJ9@ralph.baldwin.cx> User-Agent: KMail/4.14.2 (FreeBSD/10.1-STABLE; KDE/4.14.2; amd64; ; ) In-Reply-To: <201504271954.t3RJsOpO013326@glazunov.sibelius.xs4all.nl> References: <4032488.W8nPzteMFC@ralph.baldwin.cx> <2013405.YhOVhnvfYq@ralph.baldwin.cx> <201504271954.t3RJsOpO013326@glazunov.sibelius.xs4all.nl> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-IsSubscribed: yes X-SW-Source: 2015-04/txt/msg01018.txt.bz2 On Monday, April 27, 2015 09:54:24 PM Mark Kettenis wrote: > > From: John Baldwin > > Date: Mon, 27 Apr 2015 15:16:50 -0400 > > > > On Monday, April 27, 2015 08:10:18 PM Pedro Alves wrote: > > > On 04/26/2015 02:24 AM, John Baldwin wrote: > > > > Add a wrapper for add_target in fbsd-nat.c to override target operations > > > > common to all native FreeBSD targets. > > > > > > > > gdb/ChangeLog: > > > > > > > > * fbsd-nat.c (fbsd_pid_to_exec_file): Mark static. > > > > (fbsd_find_memory_regions): Mark static. > > > > (fbsd_nat_add_target): New function. > > > > * fbsd-nat.h: Export fbsd_nat_add_target and remove prototypes for > > > > fbsd_pid_to_exec_file and fbsd_find_memory_regions. > > > > * amd64fbsd-nat.c (_initialize_amd64fbsd_nat): Use fbsd_nat_add_target. > > > > * i386fbsd-nat.c (_initialize_i386fbsd_nat): Likewise. > > > > * ppcfbsd-nat.c (_initialize_ppcfbsd_nat): Likewise. > > > > * sparc64fbsd-nat.c (_initialize_sparc64fbsd_nat): Likewise. > > > > > > OOC, any reason you didn't instead do it like: > > > > > > struct target_ops * > > > fbsd_nat_target (void) > > > { > > > struct target_ops *t = inf_ptrace_target (); > > > > > > t->to_pid_to_exec_file = fbsd_pid_to_exec_file; > > > t->to_find_memory_regions = fbsd_find_memory_regions; > > > return t; > > > } > > > > > > and then use fbsd_nat_target instead of inf_ptrace_target > > > directly? > > > > > > This maps a little better to a C++ world. > > > > > > linux-nat.c does it the way you did as it keeps a separate > > > linux_ops target instance around. > > > > I was probably just using linux-nat.c as a reference. One thing that > > confuses me about the linux-nat target is that it keeps linux_ops > > around so that it can call the original methods that it overrides, > > and yet for a few methods it also uses a local 'super_foo' variable > > to call an original method. I think that those are both doing the > > same thing, but perhaps there is some subtlety I'm missing? > > > > I do use a 'super_wait' to call ptrace's wait method in the second > > patch in this series, so I could certainly change this to return a > > target rather than modifying an existing one if that is preferred. > > I'd say the linux-nat.c code is a bad example and recommend looking at > the obsd-nat.c code instead. The linux-nat.c code is so complicated > because of all the workarounds needed to support threads. The > linux_ops stuff is pretty much an artifact of those workarounds. > > I found that to add threads-support I did need to make modifications > to the _wait function that made it hard to re-use the > inf_ptrace_wait() code. Sometimes code duplications just is the right > answer. FWIW, obsd-nat.c (which I have looked at a bit), also uses a wrapper around add_target rather than creating a generic OpenBSD native target. To change the FreeBSD native targets I think would be an invasive change since they use platform-specific native targets that are pan-BSD as their initial target (e.g. amd64bsd_target) and customize from there. To make fbsd_nat_target work I would need to rework things like amd64bsd_target to modify an existing target instead of returning a new one I think (which would also mean changing all the other BSD native targets). -- John Baldwin