From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 845A0439011 for ; Tue, 3 Mar 2026 14:37:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772548627; cv=none; b=NZCTzpv5jBUchPammNncdrvixVvPjZDPODbSqBhIsQPAUfh2I+okkqNkR3I22VJbdCSso0Yrr4081iZF95v89eSC7/hEnWcY3izKaThiq+IaHlVC094OsQEAILATBb5QuWlnX42hyDXUXEYiRGWxSJ8NrK0djjxqW/X61s7riZk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772548627; c=relaxed/simple; bh=0TZLIkfh05f/06OhPJ7VuJPdoPGGywAH21cm+Guc7MI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=MjgVHNBbGL+hLLIZiWpAx6Ozh9/mjXKMgMGFstClzvU1D8P/I/vklF5BCHZbeBQxseMXAKVD5qVNI3fduSMgwTx/JkpwZchtgv1EraZBm82UyCwTASOQtBfv/kbOuIj2ZZIhGJh9Ytb4hhcXoHj23J8kosb4PQBYSWGmSaP39+A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qAEmIkWn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qAEmIkWn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D6EFC2BC9E; Tue, 3 Mar 2026 14:37:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772548627; bh=0TZLIkfh05f/06OhPJ7VuJPdoPGGywAH21cm+Guc7MI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=qAEmIkWnDDn5ueG/a3NDrHs6t0atLj3znh+FsHVdzpk2bHuO1CeMy4UvptZwOCvn0 OVGz8ID8nxYQn3/Detum1y5eQNYoSwXjULFZoyrjCK6LUtyuDRBGjmucwXKjM9ZOsI XsIppBefQnl/QqHvhD9uIkkfu5M7OzW+grxUz4CpGKFGHjc/Um8tzH/Z8ZO0M2+2ci crASlkXu8IEgdUXaWFMArK8rDu7m+J6sHBAO6bmjmAe2id1LFQ0s7X3Ijgs9rEHPUt 6LMrroL7WWU3cAAw+qaddl1af6u24aGYxmWgXFgzV9Tl2ju5HPWtLNq/4cqNIzmEic 9eiEYnrvuDm7w== From: Thomas Gleixner To: Nathan Chancellor Cc: LKML , Anna-Maria Behnsen , John Stultz , Stephen Boyd , Daniel Lezcano , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , x86@kernel.org, Peter Zijlstra , Frederic Weisbecker , Eric Dumazet Subject: Re: [patch 20/48] x86/apic: Enable TSC coupled programming mode In-Reply-To: <20260303012905.GA978396@ax162> References: <20260224163022.795809588@kernel.org> <20260224163430.076565985@kernel.org> <20260303012905.GA978396@ax162> Date: Tue, 03 Mar 2026 15:37:03 +0100 Message-ID: <87jyvtyo6o.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Mon, Mar 02 2026 at 18:29, Nathan Chancellor wrote: > > After this change landed in -next as commit f246ec3478cf ("x86/apic: > Enable TSC coupled programming mode"), two of my Intel-based test > machines fail to boot. Unfortunately, I do not think I have any serial > access on these, so I have little introspective ability. Is there any > information I can provide or patches I can test to try and help figure > out what is going on here? I have attached the output of lscpu of both > machines, in case there is some common thread there. Grmbl. I stared at it for a while and I have a suspicion. Can you try the patch below and also provide from one of the machines the output of dmesg | grep -i tsc In case that does not work, I'll send a debug patch in reply to this mail. Thanks, tglx --- --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -404,6 +404,7 @@ static void tk_setup_internals(struct ti */ clocks_calc_mult_shift(&tk->cs_ns_to_cyc_mult, &tk->cs_ns_to_cyc_shift, NSEC_PER_MSEC, clock->freq_khz, 3600 * 1000); + tk->cs_ns_to_cyc_maxns = div_u64(clock->mask, tk->cs_ns_to_cyc_mult); } }