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Fri, 07 Nov 2025 04:01:03 -0800 (PST) MIME-Version: 1.0 References: <20251101142325.1326536-1-pasha.tatashin@soleen.com> <20251101142325.1326536-2-pasha.tatashin@soleen.com> In-Reply-To: From: Pasha Tatashin Date: Fri, 7 Nov 2025 07:00:27 -0500 X-Gm-Features: AWmQ_bkI8wIkZ7GC8hYGylBjaXrBxtU3ZeBWwhoHk2_ITShMsozqrZ6SHuSvZSc Message-ID: Subject: Re: [PATCH v9 1/9] kho: make debugfs interface optional To: Zhu Yanjun Cc: akpm@linux-foundation.org, brauner@kernel.org, corbet@lwn.net, graf@amazon.com, jgg@ziepe.ca, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, masahiroy@kernel.org, ojeda@kernel.org, pratyush@kernel.org, rdunlap@infradead.org, rppt@kernel.org, tj@kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A0739180002 X-Stat-Signature: 4zygzjc4mxwz9ih61zrny1jna5ammtyr X-Rspam-User: X-HE-Tag: 1762516865-682655 X-HE-Meta: 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 LMEYsy0P k6TZxciy6g9kEryYv7p4zR02Z7JzHffTdhjUbszrn8x+pGeOQEYEMkNGwtoW4J6XIf7zHrdun1tOJgZbB2J/OP59wAvuuHu1zuXYXjqi9XP6sPxbIWBLFjtwCvwPxshKoJ4MbwpOCGh0yaMzR0EURAn6k8g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Hi, Pasha > > In our previous discussion, we talked about counting the number of times > the kernel is rebooted via kexec. At that time, you suggested adding a > variable in debugfs to keep track of this count. > However, since debugfs is now optional, where would be an appropriate > place to store this variable? It is an optional config and can still be enabled if the live update reboot number value needs to be accessed through debugfs. However, given that debugfs does not guarantee a stable interface, tooling should not be built to require these interfaces. In the WIP LUO [1] I have, I pr_info() the live update number during boot and also store it in the incoming LUO FDT tree, which can also be accessed through this optional debugfs interface. The pr_info message appears like this during boot: [ 0.000000] luo: Retrieved live update data, liveupdate number: 17 Pasha