From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 4CFE441A912; Wed, 15 Jul 2026 17:18:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784135906; cv=none; b=ghGqZCREiIcVp0HJA+AYIP7c97eFqY6X0AEHKQIJZTPMjwU29XFn0W6fqjwZWqrnJkFDTOsxdTGOd4Dc5V5PEuqL5Ia0CUieejYf1jW7lVR0+ddGVUVbCJXsh1KdztFg9YJH8bERSy1rBrea00JR/N/nHz5kGwS1RgNXbYk00ns= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784135906; c=relaxed/simple; bh=Y6YCGKF2DUsNUvejqIjzPZGdYAWhHQ186qovA6chMUg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XCVH86jDBH0cXceLk2/u3bU6RrcJQF1H3bFA7Wh+MWOr/IefBHX0OCM0Czsx3y/WJ/+kFiymWfaSCsSw1lITmZIAk4XhHYLmCzyx+BKIuPQa84aF8lAoguVUVgAbsTTJFF0yWsZ8aRhzQ0r7i1z+U+D20Ylfwp/c3zDdplUyBlk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D14F1F000E9; Wed, 15 Jul 2026 17:18:22 +0000 (UTC) Date: Wed, 15 Jul 2026 12:18:21 -0500 From: Clark Williams To: Sebastian Andrzej Siewior Cc: Florian Bezdeka , Steven Rostedt , Greg Kroah-Hartman , driver-core@lists.linux.dev, linux-rt-devel@lists.linux.dev, linux-rt-users@vger.kernel.org, "Rafael J. Wysocki" , Arnd Bergmann , Clark Williams , Danilo Krummrich , Peter Zijlstra , Clark Williams , Thomas Gleixner , Jan Kiszka Subject: Re: [RFC PATCH] sysfs: Add /sys/kernel/realtime entry Message-ID: References: <20260709143108.UYeCUUcd@linutronix.de> <2026070922-kilowatt-matador-5e1c@gregkh> <20260709152214.rH1O_8SM@linutronix.de> <748a489687000b21d0e8f961fc2f9f963b0bc1d1.camel@siemens.com> <20260710115145.32729a7c@gandalf.local.home> <20260714110718.E5qV5-Hf@linutronix.de> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260714110718.E5qV5-Hf@linutronix.de> On Tue, Jul 14, 2026 at 01:07:18PM +0200, Sebastian Andrzej Siewior wrote: > On 2026-07-10 18:01:20 [+0200], Florian Bezdeka wrote: > > Depends on what you consider a valid update scenario. Updating from 6.1- > > rt with sysfs available to something like 6.18 (no sysfs anymore) will > > still break - as long as you do not (force) update userspace in > > lockstep. > > v6.1-RT to v6-18 no-rt will not provide the file. Also will not provide > ARM, PowerPC or 8250-nbcon support. So it is not just that single thing > that you "lose" if you don't apply the RT patch. It is just what you > notice because you don't use the other things. > > > I learned meanwhile that our detection moved to uname meanwhile, so this > > is not a problem for us anymore. > > Okay. So you yelled loudly that you need it, now not anymore. > > So can we state that this it does not provide anything of value, is not > considered needed and can be dropped? > > Clark, what is the status on your end? > I still carry it in v6.1-rt and v6.6-rt and don't really see a reason not to. I don't believe it's a security risk since a write to /sys/kernel/realtime gets ignored; it's just there to say that this is a PREEMPT_RT kernel. So, I'm ambivalent on the keep or drop question. I'll go ahead and clean up what I'm carrying in v6.1-rt and v6.6-rt and if we decide to keep it I'll send you the updated changes. Clark -- The United States Coast Guard Ruining Natural Selection since 1790