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Mon, 17 May 2021 03:49:04 -0700 (PDT) Received: from zen.linaroharston ([51.148.130.216]) by smtp.gmail.com with ESMTPSA id b10sm4221895wrn.9.2021.05.17.03.49.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 May 2021 03:49:03 -0700 (PDT) Received: from zen (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id CB2031FF7E; Mon, 17 May 2021 11:49:01 +0100 (BST) References: <20210505092259.8202-1-alex.bennee@linaro.org> <20210505092259.8202-6-alex.bennee@linaro.org> <87lf8to49d.fsf@linaro.org> <87im3xo3zv.fsf@linaro.org> User-agent: mu4e 1.5.13; emacs 28.0.50 From: Alex =?utf-8?Q?Benn=C3=A9e?= To: =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= Subject: Re: [PATCH v1 5/7] docs: mark intention to deprecate TCG tracing functionality Date: Mon, 17 May 2021 11:47:11 +0100 In-reply-to: Message-ID: <87eee5eiua.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::432; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x432.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "reviewer:Incompatible changes" , qemu-devel@nongnu.org, robhenry@microsoft.com, aaron@os.amperecomputing.com, vilanova@imperial.ac.uk, mahmoudabdalghany@outlook.com, minyihh@uci.edu, cota@braap.org, stefanha@redhat.com, mohamad.gebai@gmail.com, kuhn.chenqun@huawei.com, matheus.ferst@eldorado.org.br Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Daniel P. Berrang=C3=A9 writes: > On Wed, May 05, 2021 at 11:41:46AM +0100, Alex Benn=C3=A9e wrote: >>=20 >> Alex Benn=C3=A9e writes: >>=20 >> > Daniel P. Berrang=C3=A9 writes: >> > >> >> On Wed, May 05, 2021 at 10:22:57AM +0100, Alex Benn=C3=A9e wrote: >> >> >>> +TCG introspection features >> >>> +-------------------------- >> >>> + >> >>> +TCG trace-events (since 6.1) >> >>> +'''''''''''''''''''''''''''' >> >>> + >> >>> +The ability to add new TCG trace points has bit rotted and as the >> >> >> >> When you say this "has bit rotted", just how bad is the situation ? >> >> >> >> Is the TCG tracing still usable at all, or is is fully broken >> >> already ? >> > >> > Well patches 6/7 got it working for generic TCG things. I haven't been >> > able to get the architecture one working but I suspect that is some so= rt >> > of interaction between the per-arch trace header generation that I >> > haven't quite figured out yet. >>=20 >> Ahh it's since 7609ffb919 (trace: fix tcg tracing build breakage) which >> limited tcg/vcpu events to the root trace-events file. > > That commit is from release 2.10.0. > > The other commit mentioned in patch 6 (73ff061032) is from 2.12.0. > > So no one has been able to use this feature for 3+ years already. > > Is it actually worth fixing and then deprecating for 2 releases before > deleting, as opposed to just deleting the broken code today on basis > that it can't have any current users ? Well I can get it up and running with the aforementioned patches and it seems reasonable to give some notice. I'm happy to defer to Stefan here though as it's his sub-system. > > Regards, > Daniel --=20 Alex Benn=C3=A9e