From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C25AE314B95 for ; Fri, 7 Nov 2025 23:36:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762558574; cv=none; b=Gset3NxHAgJmbYW+RyXCkuMS5eA27+6Udyb/ssIqizQ+3LIu2yZ2hI1XimFk/idk7sZ2cM7eonDYuUg0tY1ZH17IlBFJdimKzIuZUB9AWqfAwzcQp+285gnjsyTjCKvq4r7EvvxiYBljrYEA25GzVJEn7aBeumygJw5SPCDsTVo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762558574; c=relaxed/simple; bh=0lY64VJ/ffa3/Z9Qv1liUMSAYVI0NdChWyMUC9rTTxo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MH2vhlWAe3O5f25ltt/jwo3LpiYLGh05fEAaSD1q42MVU7CaE86ni2yoJvARWUifU+K8KOz7AUgL9kjvNKDJ2uaZPhANZh0KrQhhK1NScWRk+rlwUTHyJP/qY5DUtYCvmAxYLdRvUHGxkTNDvyblrXEqcpVbn+sS7Ih6qBMpgp4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=mIiN5q75; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="mIiN5q75" Message-ID: <029090cf-9a4d-4f79-b857-04c3ada83323@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1762558560; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0qQGWs6LpN4unSynWVZhzKi98tWARU4nt/0dAsCAu7Q=; b=mIiN5q75lCcf4two/6jp3fr1UONOvcNFCZELHORZjTZkHsbOJO9x9ckTDX0TcH1xMG5rhV QkiPWcQQN3A01vmtyJlDXfZfzuXQEcmdyLTiQ4ZPqy2Hx8ncAy0QNM8yZvrVetu+BsV5zo 4n2Gew0vzxo30idUCWKmG8Dbk1su/Sg= Date: Fri, 7 Nov 2025 15:35:55 -0800 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v9 1/9] kho: make debugfs interface optional To: Pasha Tatashin 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 References: <20251101142325.1326536-1-pasha.tatashin@soleen.com> <20251101142325.1326536-2-pasha.tatashin@soleen.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Yanjun.Zhu" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 11/7/25 4:02 AM, Pasha Tatashin wrote: > On Fri, Nov 7, 2025 at 7:00 AM Pasha Tatashin wrote: >>> 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 > Forgot to add link to WIP LUOv5: > [1] https://github.com/soleen/linux/tree/luo/v5rc04 Thanks a lot. I’ve carefully read this commit: https://github.com/soleen/linux/commit/60205b9a95c319dc9965f119303a1d83f0ff08fa. To be honest, I’d like to run some tests with who/luo, including the selftest for kho/luo. Could you please share the steps with me? If the testing steps have already been documented somewhere, could you please share the link? Best Regards, Yanjun.Zhu