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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767385404; bh=36h+gzQOCGURAdbtJyCuaVTakIb422pTXIoravRz/yA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=C850m0yzR3hfqz7dBIq6J71yU2NNbzw4mZaZTNyPS1TZV7qYNGtTDRPG8kpI1KJZU ofuE0e2/hKuY+6qQQ+lwQ0cj+QRkeNR26LRPa8WC2Y0oXilcU6aovdOyDqulr10/0J 5w+ird2Y68JVQc1u6tcW/DP7po+/gYn1EcUYwlJp6jHPGn2Yy/S+qSk+7FuXSSkyt5 nCJuLXK565YOlUy2SvzN3oX2xAQGgxxkic4YaKhFFok0GamRAPMXKe6yrSoNzIPeAe i1FlTFFmTkhtejMhNuCFQjPyckllVuKw4dtWQQ8M+NlfERKco0rQC6McmwA9iTE7T4 hcbWYVbQZ+9zw== From: Pratyush Yadav To: Breno Leitao Cc: Alexander Graf , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, usamaarif642@gmail.com, rmikey@meta.com, clm@fb.com, riel@surriel.com, kernel-team@meta.com Subject: Re: [PATCH v2 2/2] kexec: history: track kexec boot counter In-Reply-To: <20260102-kho-v2-2-1747b1a3a1d6@debian.org> (Breno Leitao's message of "Fri, 02 Jan 2026 06:53:24 -0800") References: <20260102-kho-v2-0-1747b1a3a1d6@debian.org> <20260102-kho-v2-2-1747b1a3a1d6@debian.org> Date: Fri, 02 Jan 2026 21:23:18 +0100 Message-ID: <86o6nb7oi1.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: EC12B180005 X-Stat-Signature: uy4fac878xtp87fi5xpwjhwuyo7qt93f X-HE-Tag: 1767385405-593426 X-HE-Meta: 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 dxx3H6sG 8W7SXR6CsA1MboUIPgWxPSA3PalZo4kHM4W4hfqbaJNY7ScRfVkwrTPhWmtq1ZYXYzEqDesfrlC8HTXTG/Amdx4XIZ/EApc/TdUqNa8FRD3Fp1pLBYufyAAKyiFWM3VqQq7OsVfbYqDr5KbLyfiQCd8+7l05WMO4pdvwx7eQhjJeTK6o= 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: On Fri, Jan 02 2026, Breno Leitao wrote: > Track and display the number of kexec boots since the last cold reboot Nit: this does not track kexec boots, it tracks KHO boots. None of this can work on normal kexec boots. Can you please update the wording to make that clear? > when CONFIG_KEXEC_HISTORY is enabled. > > This extends the previous kernel release tracking feature by adding > a counter that increments with each kexec boot. The counter provides > visibility into the kexec chain depth, which is useful for understanding > boot history in production environments. > > Add a new property, "kexec-count" in KHO FDT alongside the existing > "previous-release" property. The counter is: > > - Initialized to 0 when kho_in is instantiated. > - Incremented by 1 on each subsequent kexec. > - Printed alongside the previous kernel release version. > > The counter is stored as a 32-bit unsigned integer in FDT format and is > only active when CONFIG_KEXEC_HISTORY is enabled. We have such a counter for LUO as well from the properly "liveupdate-number". If you're using LUO, why can't you use that counter directly? If you're not using LUO, I'm curious, what's your use case? Right now KHO only supports reserve-mem outside of LUO. Is that what you plan to use? Also, do we want to keep both counters independently? Or do we have one and drop the other? Pasha, what do you think? [...] -- Regards, Pratyush Yadav