From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (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 37EDC1DE3DC for ; Mon, 10 Nov 2025 00:21:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762734077; cv=none; b=UEuu9d0M0uSdcKgN9/lidAIZfifcseHwixUOnywhXZaxxvKOhxZvIMgZcwFBUndaDI6prH2X76adhOCEZWZpsebtIwfxsyCYDTtbXS088N0x8cb/JQCJhNZBidDguQ747WrbnIEulCd4CAHmi9PPRd2yMl4Dhgaq77wsE+kwKkU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762734077; c=relaxed/simple; bh=MS7Cf/KMp3LIQkV/zy5GKazQnzumkX1n8Ct0PmoQalU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JcKe4MZX/37kiszem49Gymkb4+J1hMcUGsK014C5BpzM5IuFs304hMGiyRc+HqCFDf/tcelZBxEEvF+ViwLsQl/oaLmCHFuYY2brHe12IfOpGvz03zCnJF8r/QhsMGTKUciCGXjsZ7thLLclcrT6ZQTq3IONxjsm7krllP00UxE= 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=aFVEiWeL; arc=none smtp.client-ip=91.218.175.170 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="aFVEiWeL" Message-ID: <442fa82e-16ef-4bde-84eb-743450222468@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1762734062; 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=jLBZG12EpOweg5W//dmheHVzJBlI9SLwueSdt6kZhp0=; b=aFVEiWeLxQUK2ISXdf52J2BDzGtfH3DLAlz7RqIMEVvL9ZhZRM6nGB2fRlFMFljDGu5yXu JcC07geo4luDBuNKUq/6FdonyAlA8GeAPnuUN8ofevO0Hyxet8ILg/fDdsxUkBh4xp+5kB 9PLUGv7mP+wX6RNN85JBMCCoTtQXbfg= Date: Sun, 9 Nov 2025 16:20:56 -0800 Precedence: bulk X-Mailing-List: linux-kernel@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> <029090cf-9a4d-4f79-b857-04c3ada83323@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Zhu Yanjun In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 在 2025/11/8 10:13, Pasha Tatashin 写道: > On Fri, Nov 7, 2025 at 6:36 PM Yanjun.Zhu wrote: >> >> 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? > Currently the test performs in-kernel tests for FLB data, it creates a > number of FLB for every registered LUO file-handler, which at the > moment is only memfd. > > It works together with any of the kexec based live update tests. In > v5, I introduce two tests: > luo_kexec_simple > luo_multi_session > > For example, with luo_multi_session: Hi, Pasha I enabled "CONFIG_LIVEUPDATE=y" # ./luo_multi_session 1..0 # SKIP Failed to open /dev/liveupdate. Is the luo module loaded? # ls /dev/liveupdate ls: cannot access '/dev/liveupdate': No such file or directory # grep "LIVEUPDATE" -inrHI /boot/config-`uname -r` /boot/config-next-20251107-luo+:349:CONFIG_LIVEUPDATE=y /boot/config-next-20251107-luo+:11985:CONFIG_LIVEUPDATE_TEST=y I made tests on FC42. But /dev/liveupdate is missing. Thanks Yanjun.Zhu > # ./luo_multi_session > # [STAGE 1] Starting pre-kexec setup for multi-session test... > # [STAGE 1] Creating state file for next stage (2)... > # [STAGE 1] Creating empty sessions 'multi-test-empty-1' and > 'multi-test-empty-2'... > # [STAGE 1] Creating session 'multi-test-files-1' with one memfd... > # [STAGE 1] Creating session 'multi-test-files-2' with two memfds... > # [STAGE 1] Executing kexec... > > ... reboot ... > After reboot: > > $ ./luo_multi_session > # [STAGE 2] Starting post-kexec verification... > # [STAGE 2] Retrieving all sessions... > # [STAGE 2] Verifying contents of session 'multi-test-files-1'... > # [STAGE 2] Verifying contents of session 'multi-test-files-2'... > # [STAGE 2] Test data verified successfully. > # [STAGE 2] Finalizing all test sessions... > # [STAGE 2] Finalizing state session... > # > --- MULTI-SESSION KEXEC TEST PASSED --- > > Dmesg data, shows that in-kernel live update test was also successful: > > [ 0.000000] luo: Retrieved live update data, liveupdate number: 1 > [ 0.034513] liveupdate test: test-flb-v0: found flb data from the > previous boot > [ 0.034517] liveupdate test: test-flb-v1: found flb data from the > previous boot > [ 0.034518] liveupdate test: test-flb-v2: found flb data from the > previous boot > [ 0.676891] liveupdate test: Registered 3 FLBs with file handler: [memfd-v1] > > Pasha > >> Best Regards, >> >> Yanjun.Zhu >> -- Best Regards, Yanjun.Zhu