From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 44423 invoked by alias); 16 Nov 2018 19:37:00 -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 44399 invoked by uid 89); 16 Nov 2018 19:36:57 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,SPF_PASS autolearn=ham version=3.3.2 spammy=U*gdb-patches, gdb-patches@sourceware.org, HTo:U*jhb, gdbpatchessourcewareorg X-HELO: eggs.gnu.org Received: from eggs.gnu.org (HELO eggs.gnu.org) (208.118.235.92) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 16 Nov 2018 19:36:56 +0000 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gNjv7-0002xT-NH for gdb-patches@sourceware.org; Fri, 16 Nov 2018 14:36:54 -0500 Received: from fencepost.gnu.org ([2001:4830:134:3::e]:51087) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gNjv2-0002va-HS; Fri, 16 Nov 2018 14:36:47 -0500 Received: from [176.228.60.248] (port=2321 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1gNjv0-00067P-Qp; Fri, 16 Nov 2018 14:36:44 -0500 Date: Fri, 16 Nov 2018 19:37:00 -0000 Message-Id: <83va4wu852.fsf@gnu.org> From: Eli Zaretskii To: John Baldwin CC: gdb-patches@sourceware.org In-reply-to: <36bd0ca7-ffb9-3cbe-584f-d1e1e54b6034@FreeBSD.org> (message from John Baldwin on Fri, 16 Nov 2018 09:43:56 -0800) Subject: Re: [PATCH v3 2/3] Add an optional "alias" attribute to syscall entries. References: <20181109200432.84491-1-jhb@FreeBSD.org> <20181109200432.84491-3-jhb@FreeBSD.org> <83efbuattx.fsf@gnu.org> <36bd0ca7-ffb9-3cbe-584f-d1e1e54b6034@FreeBSD.org> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e X-IsSubscribed: yes X-SW-Source: 2018-11/txt/msg00259.txt.bz2 > Cc: gdb-patches@sourceware.org > From: John Baldwin > Date: Fri, 16 Nov 2018 09:43:56 -0800 > > > IMO, this is very abstract and too vague to be useful. Since we won't > > have anything more detailed in the manual, would it be possible to > > make this description more concrete? E.g., how about using some of > > the text and examples you used in your description of the issue: > > Ok. I wasn't too happy with my first attempt either. I've tried to give > some more detail while not making it too long. Let me know what you think: > > * System call catchpoints now support system call aliases on FreeBSD. > When the ABI of a system call changes in FreeBSD, this is > implemented by leaving a compatibility system call using the old ABI > at the existing number and allocating a new system call number for > the new ABI. For example, FreeBSD 12 altered the layout of 'struct > kevent' used by the 'kevent' system call. As a result, FreeBSD 12 > kernels ship with both 'kevent' and 'freebsd11_kevent' system calls. > The 'freebsd11_kevent' system call is assigned an alias of 'kevent' > so that a system call catchpoint for the 'kevent' system call will > catch invocations of both the 'kevent' and 'freebsd11_kevent' > binaries. This ensures that 'kevent' system calls are caught for > binaries using either the old or new ABIs. LGTM, thanks.