From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.freebsd.org (mx2.freebsd.org [96.47.72.81]) by sourceware.org (Postfix) with ESMTPS id 1F2AB385E44A for ; Thu, 29 Jul 2021 16:04:01 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 1F2AB385E44A Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=FreeBSD.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits)) (Client CN "mx1.freebsd.org", Issuer "R3" (verified OK)) by mx2.freebsd.org (Postfix) with ESMTPS id D994899A2B; Thu, 29 Jul 2021 16:04:00 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4GbFhJ5VW5z3FpL; Thu, 29 Jul 2021 16:04:00 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from John-Baldwins-MacBook-Pro.local (ralph.baldwin.cx [66.234.199.215]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 1F98E20410; Thu, 29 Jul 2021 16:04:00 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: [PING][PATCH,v5][AArch64] MTE corefile support To: Simon Marchi , Catalin Marinas , Joel Brobecker Cc: david.spickett@linaro.org, Luis Machado via Gdb-patches References: <20210518202047.3492211-1-luis.machado@linaro.org> <20210601174519.4157316-1-luis.machado@linaro.org> <20210711142200.GA637634@adacore.com> <20210714130702.GA9376@arm.com> From: John Baldwin Message-ID: <8d1a94c0-163e-ea99-7d9d-7b05c79b47fc@FreeBSD.org> Date: Thu, 29 Jul 2021 09:03:58 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-4.0 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, NICE_REPLY_A, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 29 Jul 2021 16:04:02 -0000 On 7/28/21 7:26 PM, Simon Marchi via Gdb-patches wrote: > On 2021-07-14 9:07 a.m., Catalin Marinas wrote: >> On Sun, Jul 11, 2021 at 07:22:00AM -0700, Joel Brobecker wrote: >>> Luis is trying to have this new feature ready for the GDB 11.1 >>> release. As I understand it, the AArch64-specific part has already >>> been approved, so he's waiting for someone to review the rest of >>> the changes. Is there a Global Maintainer who would feel comfortable >>> doing so and who would have the time? >> >> I'm a Linux kernel maintainer, so not much for me to review on the gdb >> front. But feedback from the gdb maintainers would be appreciated. >> >> W.r.t. upstreaming the feature in gdb, I'd wait until the Linux >> counterpart is merged. We agreed in principle on the ABI but I wouldn't >> consider it stable until the feature hits a kernel release. > > I reviewed a few of the previous iterations, and there were only really > some nits remaining, so I am confident that this version is OK, from a > GDB point of view. > > ABI-wise, I tend to agree with Catalin: as long as it's not in a > released kernel, the format *could* change. But is it a problem in > practice? Let's say this happens: > > - We merge support for MTE core files in GDB 11 > - The format gets changed, merged and released in a kernel > - We fix GDB 12 based on the new format > > Then GDB 11 users end up with a GDB that can't read MTE notes. But had > we not merged the support for it, they would also end up with a GDB that > can't read MTE notes. In both cases, we'll tell them "upgrade to GDB > 12" (once it's released). > > If we merge support for MTE in core files now and if the format > doesn't change, everybody is happy. I guess it depends on how likely it > is that the format is going to change. I think the format is suitable and probably won't need to change. I have an interest in using it for another type of memory tags (CHERI & Morello) and this format will support those (and in fact it would even support an architecture with multiple memory tags). -- John Baldwin