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 2C22E3E8C78 for ; Mon, 17 Aug 2026 10:00:54 +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=1786960858; cv=none; b=KZ3Xz5mnqRQKPtCd0PW9Rd2QfrZEdBhRzFLjXJ7nUA6VMsGapJ7o0UeIJFp5tqEbCfFLdmvzJRQj6lv2DdF4vjoeUoi+tEBqKVizhg2JB1tgLbG2S/nJLc7He3rAHfzBXwtbGOOo7EbwrCa0YMaKOorQkm20u9D9uOLMYgkQt3U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786960858; c=relaxed/simple; bh=mFh1EMBsJgEQ6eOrIUASpwy8TGLjSL94u5zlFTjU4PA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=h9CfHZfkVGX97dabc6kyD2foNqjjCzFD1cGRNzGdU0k/SxcSztGSUNNFrNxiUtJfwv7FLo6/OD+azCEkB9lIfLSEaimMKnSHTT3ApyPDyAJBxDKBvYe/IpJWBJ85M9+u82BkZG7Gev6KwK8A9cslO+QCr1D2dmorwStV/0uT2Yk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GslwOQk2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GslwOQk2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79FEB1F000E9; Mon, 17 Aug 2026 10:00:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786960852; bh=oe2LcLGKUvGGia90vmQmNdMRkoxH1sGQs69KVRedip8=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=GslwOQk2DwxkJ/H6dHT+RmwV8j2XMGb8gu06Ews8xT7ygwkoPhOYp86LO4Es4Z+O9 ePwS1u5qC+0haGM5n3kM9jFv19iruaNZExCHS8Gjf3EDX1fRdTwc3bD5fD0WmkOtD8 +/fzxNoNhAM4ZB+QU7vXLvPOQTdX3P+hvX5T3SJeCiP0Mb7pqGUPjFTgqLTHOWT0nj BTES0w7pqRt99dkseOqZfKLpmw0u9AT0GMNI0RHG6sPo+uF9jjEVbJpC8c5o/yer6D mjqLEAUmBW+d96BHTPl8Yx/JdydLK4yqZ/LxZW7xmm4LxVgNiqBWiVj/HreYOEHswc /kyyva2gspJFA== From: Thomas Gleixner To: David Kostial , "x86@kernel.org" Cc: "linux-kernel@vger.kernel.org" Subject: Re: [BUG] x86/tsc: ~1 second TSC skew when bringing a secondary CPU online on Ryzen 7 8840HS In-Reply-To: <2058267156.513331.1786817844981@mailbusiness.ionos.de> References: <2058267156.513331.1786817844981@mailbusiness.ionos.de> Date: Mon, 17 Aug 2026 12:00:49 +0200 Message-ID: <87mrulkqwe.ffs@fw13> 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 Sat, Aug 15 2026 at 20:17, David Kostial wrote: > smpboot: Booting Node 0 Processor 1 APIC 0x1 > TSC synchronization [CPU#0 -> CPU#1]: > Measured 3360957369 cycles TSC warp between CPUs, turning off TSC clock. > tsc: Marking TSC unstable due to check_tsc_sync_source failed > TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'. > clocksource: Switched to clocksource hpet .... > I'm not sure whether the root cause is firmware/AGESA or whether there > is anything x86/tsc should handle differently here. That's a firmware problem. The firmware messes up the TSC synchronization. The kernel can't do anything about this as the CPU does not have the TSC_ADJUST MSR. We tried to write to the TSC MSR directly, but that turned out to be fragile and unreliable so we restricted the fixup attempts to CPUs which have the TSC_ADJUST MSR. Thanks, tglx