From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (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 8D2FA16E863 for ; Mon, 17 Mar 2025 15:24:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.60.130.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742225070; cv=none; b=bKiZrX2xTvUhE0XVU3+DB3p3OJm4UWD6mihpDc/0HtZn99QzB/X4Av7aFbt4eQ4PDJ4uK9X/b4+RoCm0CR+LNFy9f5SpTS/YShKXrkVuskKW6x2+E9CeiadQliJ4mE6hih6W6/jUe7o+Mvrfnvf6G9G6Rw2ecV3GPY0+UKAcRyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742225070; c=relaxed/simple; bh=DEjJ25Es6BM7xj6uskcT/d+9Z4ZClbxmOJw9QyYt10w=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=exxGZS4uUDStsQrDXMzKvL/n3aMeYfc0eG9tGjHQ6TbAJwPpT1KA4eLAxcNkPquchWbdyNDF+ifGPJWDAo/DGHw8ACWil4u2irwF+CKr0k1oAVuBzDbpUFKQaCdtRwcnTUEzv62T/NPGY2W/u+6sZoxx8bi0D2q77xmRw8obm00= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=rWadFXma; arc=none smtp.client-ip=178.60.130.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="rWadFXma" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; 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:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=8QDwo5kF1JSBFzHwNUnF/K8mjZQ2hop0jQzunjRmUXo=; b=rWadFXma1eVV5kMAZ48rVjbhTT ybNZ5xCy5ttZZ1vW0pDq5cZswJwzZPdjgvOSce4B1xq1CgWHwv+cYg88DCMt0NY00jF8a0uV7XS0/ t7Rsi3LE+GAGXrmpdI9q9YuEOYI0cnjKdeDYXm/N1xIVY/QNRQ5DbmqpeClFufjGP+WiqSqWGMNfp HEbBvidDlZwzk2xXC8xbeEYcXm4dzIhchSSL5UNYpDYy2BZ8kKMw75FjQs+0GWnyaRTWJs99ipNsy xx0LR9Xy3A3VZPa39SgAer+meJV4EL5KyXYJALwx+YNRvg/JLsojZBJS+TV7+trg5gZSm2/6YQrhf T6tDgZMQ==; Received: from [187.90.172.172] (helo=[192.168.1.60]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1tuCKC-002Hnk-9k; Mon, 17 Mar 2025 16:24:20 +0100 Message-ID: Date: Mon, 17 Mar 2025 12:24:15 -0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH] x86/tsc: Add debugfs entry to mark TSC as unstable after boot Content-Language: en-US To: Borislav Petkov Cc: x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, hpa@zytor.com, kernel@gpiccoli.net, kernel-dev@igalia.com References: <20250226132733.58327-1-gpiccoli@igalia.com> <20250317144028.GEZ9g0XPSkOQU7A-nO@fat_crate.local> <20250317151446.GFZ9g8Zi3qmBwOTuz_@fat_crate.local> From: "Guilherme G. Piccoli" In-Reply-To: <20250317151446.GFZ9g8Zi3qmBwOTuz_@fat_crate.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 17/03/2025 12:14, Borislav Petkov wrote: > [...] >> The same that happens if today someone marks it as unstable via >> command-line, right? You will see that on logs, and could simply reply >> that the user marked as unstable themselves, so..no bug at all!! >> >> But let's think the other way around: what if some user marks TSC >> unstable via debugfs, later on runtime, and with that, unveils a real > > I don't understand what you mean here. > Oh, I meant that: since the behavior of other components (like tracing clock) is different if TSC is marked as unstable (a) on boot time, through command-line, (b) some time after boot, like on watchdog skews (or using this debugfs approach), we may as well have some user marking it unstable through debugfs and due to that, finding a real bug somewhere, that we can fix it! >> bug as [1] and then, we can then fix it? That would be a win heheh > > No, marking the most important clocksource on x86 deliberately as unstable > better scream bloody hell in dmesg. But regardless, I'm not convinced this is > nearly as needed to have upstream. Just use it locally or cmdline. > > Thx. > OK Boris, thanks for the feedback - if you don't see much value in this one, let's forget about that - can always change locally as you said. Cheers, Guilherme