From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ms.lwn.net (ms.lwn.net [45.79.88.28]) (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 77C2523BD02; Mon, 3 Nov 2025 23:33:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.79.88.28 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762212803; cv=none; b=g4DQWfoxxEFWaQPLQlnuCfME6s07ZRhtdaVMkVI6Swlagpirjv35KEb19XzD/GbJe9LIyhXPvytjzhe/FPqLiI6puLrHx4EJL02J26zUu5ZD/XCBhz2ipOuDXwyoJyZK5VvWUS+6TenNbkFogKfFFUFDpRqyfuAvaCSrO3cbhtM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762212803; c=relaxed/simple; bh=Pl6H9vJe7acg1O6MR3J9UUbyidoSPhERCxM1FXyC3PI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=tnWb7gVLxr7vZIiRk6ukaeazUitrUwLiD6uvA8zkfVgi86PRnXDOF9LWSqLmRa7HgSZnDsECGvGpa0cSFyxH7vN+Nk0MhNdluTaq7eJZmR5BKzJzVPIa07uuBA8vZMNm/uj10VSdVMGOQHnaQfODxu1xd927PCqmfW3nR/+7WLo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net; spf=pass smtp.mailfrom=lwn.net; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b=A4WT2590; arc=none smtp.client-ip=45.79.88.28 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lwn.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b="A4WT2590" DKIM-Filter: OpenDKIM Filter v2.11.0 ms.lwn.net 8AED740AED DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lwn.net; s=20201203; t=1762212801; bh=7hPQDATXasc6TszX/hLxGIMFy6caQRz+O9eoOhPx3gQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=A4WT2590Lleb50KL0+rBO6gEF+qB7LQt6icP7bKDRUeFvjydw4dbSTh7IhXGdGmKK 6yQpp9qiUpeniNy5O89XYhE5ZVyRT46czJpKyRsaokPYfY01iknOSI8gkljfm7z4eG 9UurPhH9LkjrGOITX8GKqOikuQUlBEklN5uKiYMYpoSecqQxSJuCnZ1jqNJA6r2Si5 xy3UN3iuDWGEaCe9QaloP92godZR6czpJhZdgJoX4sAzPegUtOMh91KEGIjOPFu+Tm Dv0v/jlNJBjjsXml61Ak/athlvDT59w1AltRz0Xc6aVMb9MTd1AbEf3qghPX+XXSsv Ff1DE0VboRV6g== Received: from localhost (unknown [IPv6:2601:280:4600:2da9::1fe]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 8AED740AED; Mon, 3 Nov 2025 23:33:21 +0000 (UTC) From: Jonathan Corbet To: Bagas Sanjaya , Linux Kernel Mailing List , Linux Documentation , Linux Serial Cc: Cengiz Can , Bagas Sanjaya , Tomas Mudrunka , Jiri Slaby , Greg Kroah-Hartman , Anselm =?utf-8?Q?Sch=C3=BCler?= , Randy Dunlap Subject: Re: [PATCH v3] Documentation: sysrq: Rewrite /proc/sysrq-trigger usage In-Reply-To: <20251023014102.16777-1-bagasdotme@gmail.com> References: <20251023014102.16777-1-bagasdotme@gmail.com> Date: Mon, 03 Nov 2025 16:33:20 -0700 Message-ID: <87jz06bsjj.fsf@trenco.lwn.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Bagas Sanjaya writes: > /proc/sysrq-trigger usage documentation (in "On all" section) states > that it is not recommended to write extra characters to it. The sentence > may imply a contradiction to previous sentence which writes that such > characters are ignored. > > Rewrite the description. > > Link: https://lore.kernel.org/lkml/7ca05672-dc20-413f-a923-f77ce0a9d307@anselmschueler.com/ > Signed-off-by: Bagas Sanjaya > --- > Changes since v2 [1]: > > - Keep /proc/sysrq-trigger future API change note (Tomas) > > Anselm: Do you object to the rewrite? It still seems confusing... > [1]: https://lore.kernel.org/linux-doc/20251016103609.33897-2-bagasdotme@gmail.com/ > > Documentation/admin-guide/sysrq.rst | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst > index 9c7aa817adc72d..a88266b171aa17 100644 > --- a/Documentation/admin-guide/sysrq.rst > +++ b/Documentation/admin-guide/sysrq.rst > @@ -75,16 +75,15 @@ On other > submit a patch to be included in this section. > > On all > - Write a single character to /proc/sysrq-trigger. > - Only the first character is processed, the rest of the string is > - ignored. However, it is not recommended to write any extra characters > - as the behavior is undefined and might change in the future versions. > - E.g.:: > + Write a single character to /proc/sysrq-trigger. E.g.:: > > echo t > /proc/sysrq-trigger > > - Alternatively, write multiple characters prepended by underscore. > - This way, all characters will be processed. E.g.:: > + Only the first character is processed; any following characters are > + ignored for now, which might change in the future. > + > + Alternatively, to write multiple characters, prepend them with an > + underscore so that these all will be processed. E.g.:: You're still saying that following characters are ignored, then give an example where they are not: > echo _reisub > /proc/sysrq-trigger So, for me, this still isn't really right. This, I think, is a holdover from before, but I have to point out that: > echo t > /proc/sysrq-trigger Does *not* write a single character: it writes "t\n". jon