From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 84236296BA7; Tue, 14 Oct 2025 17:57:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760464668; cv=none; b=anrFmagFqCdmtKEux/Sed90GFh0A/qyFeZADSh2+WD/VlHyBJ/Q3Ezqv3z/P++MPJLCx3rkSRAPr34EO5s/i/cqEhTpEFD6/K75iXWoQ9DWhPfM4VLi/R0+pQkQMJFBV+IpSPCzwh38FM3mtwJJ5cTfntjXdXdckz+uJtCYhQpI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760464668; c=relaxed/simple; bh=+MCW3pWeUmZPyGxMrX0RxPKRd723eQqL7FGWAFlCJcY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=BMloozitSiGsv+AnOCcGR9UNBmpcMyzN/wzzi1nSKx5kgOdj7bFqIzCnEoz7aaPYRxczVOdlNhYKmOMIDGM4N7qM+MhvTIlhtTrvQFB60iP7bOSJhBTM8I2njex9W28pnug/V4wEoSAm0FjFSptnPDd0+j8Bhu01Y1N0umvljvQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=xU12w+3h; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="xU12w+3h" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Sender:Reply-To:Content-ID:Content-Description; bh=r2+wIsDTT/YrPhAA/dkQ7vm5iMhdp0goW9on/CiFr/g=; b=xU12w+3hNb9ltRQ40yzAiQ8eEX eLwUXtuCe25tCXZsYxXQTs+wkOHgDCKEcULtHzYWGIvnZesaKEsFuXaZrLofohWUYKsGPhrFqV9Z0 370bdaiGaI2xWJuJRLXFIOO+Nf3bY728T0JZOGqGLelCLpSOUg+YKO9ojPcADR84Ogh5J4QqY8yRh otLPq8KSHppiyeMt6/JUFFLz9LvwttJ+1ata50ti6Io3BRevw4GldC8lrbjBwLPBr7ZRY1La3BAwx Do0QiyD9dLqIyMbfchLI5eGzjVYYgwn764pH5x6e0iNt+YM905C7sM8dwnHv93J4iuLrzBGdTB9ni EYjoIj7A==; Received: from [50.53.43.113] (helo=[192.168.254.34]) by bombadil.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1v8jHN-0000000H7sL-3awZ; Tue, 14 Oct 2025 17:57:45 +0000 Message-ID: Date: Tue, 14 Oct 2025 10:57:45 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] Documentation: sysrq: Remove contradicting sentence on extra /proc/sysrq-trigger characters To: Jonathan Corbet , Bagas Sanjaya , Linux Kernel Mailing List , Linux Documentation , Linux Serial Cc: Cengiz Can , Tomas Mudrunka , Jiri Slaby , Greg Kroah-Hartman , =?UTF-8?Q?Anselm_Sch=C3=BCler?= References: <20251008112409.33622-1-bagasdotme@gmail.com> <87wm4xbkim.fsf@trenco.lwn.net> Content-Language: en-US From: Randy Dunlap In-Reply-To: <87wm4xbkim.fsf@trenco.lwn.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/14/25 7:55 AM, Jonathan Corbet wrote: > Bagas Sanjaya writes: > >> /proc/sysrq-trigger documentation states that only first character is >> processed and the rest is ignored, yet it is not recommended to write >> any extra characters to it. The latter statement is contradictive as >> these characters are also ignored as implied by preceding sentence. >> >> Remove it. >> >> Link: https://lore.kernel.org/lkml/7ca05672-dc20-413f-a923-f77ce0a9d307@anselmschueler.com/ >> Signed-off-by: Bagas Sanjaya >> --- >> Documentation/admin-guide/sysrq.rst | 4 +--- >> 1 file changed, 1 insertion(+), 3 deletions(-) >> >> diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst >> index 9c7aa817adc72d..63ff415ce85d66 100644 >> --- a/Documentation/admin-guide/sysrq.rst >> +++ b/Documentation/admin-guide/sysrq.rst >> @@ -77,9 +77,7 @@ On other >> 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.:: >> + ignored. E.g.:: > > I'm not sure this is right - there is a warning here that additional > characters may acquire a meaning in the future, so one should not > develop the habit of writing them now. After all these years, I think > the chances of fundamental sysrq changes are pretty small, but I still > don't see why we would take the warning out? but the following paragraph says: Alternatively, write multiple characters prepended by underscore. This way, all characters will be processed. E.g.:: echo _reisub > /proc/sysrq-trigger so it is confuzing. -- ~Randy