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[208.100.161.3]) by smtp.gmail.com with ESMTPSA id i11sm2732864pjl.53.2020.12.04.10.13.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Dec 2020 10:13:58 -0800 (PST) Date: Fri, 4 Dec 2020 10:13:56 -0800 From: Will McVicker To: Christoph Hellwig Cc: Jessica Yu , Masahiro Yamada , Michal Marek , Greg Kroah-Hartman , Saravana Kannan , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v2 0/2] Adds support to capture module's SCM version Message-ID: References: <20201125010541.309848-1-willmcvicker@google.com> <20201204075159.GA29752@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201204075159.GA29752@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 04, 2020 at 07:51:59AM +0000, Christoph Hellwig wrote: > I think your decription still shows absolutely no benefit for the > kernel, so I'not sure why anyone would want to waste time on this. Hi Christoph, Did you get a chance to read my earlier responses regarding the uses for in-tree modules? The biggest benefit for the upstream community is being about to get the SCM version for *any* module (including in-tree modules) in the initramfs via the sysfs node. Currently there is no way to do that and there is no guarantee that those modules in the initramfs were compiled with the running kernel. In fact, running, modinfo -F vermagic MODULENAME will return an invalid vermagic string if the same module with different vermagic strings exists in the initramfs and on disk because modinfo only looks at the module on disk (not in memory). The second most useful benefit goes hand-in-hand with MODVERSIONS. The purpose of MODVERSIONS is to create a stable interface that allows one to update the kernel and kernel modules (including in-tree modules) independently. So when developers do update their kernels independently (think for security bug fixes), the `scmversion` attribute guarantees developers that they can still identify the modules' or kernel's SCM version. I hope that helps. If not, then please let me know why these reasons "show absolutely no benefit for the kernel?" Thanks, Will