From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754668AbbFCTzh (ORCPT ); Wed, 3 Jun 2015 15:55:37 -0400 Received: from www.sr71.net ([198.145.64.142]:49936 "EHLO blackbird.sr71.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751862AbbFCTz3 (ORCPT ); Wed, 3 Jun 2015 15:55:29 -0400 Message-ID: <556F5BAF.8010303@sr71.net> Date: Wed, 03 Jun 2015 12:55:27 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: LKML , "Yu, Fenghua" , John Stultz , the arch/x86 maintainers Subject: hangs in verify_pmtmr_rate() Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I'm seeing boot hangs when trying to boot a 32-bit 4.1.0-rc5 kernel on some 64-bit CPUs (I'm not sure if it is a regression). The NMI watchdog shows init_acpi_pm_clocksource() as the last thing in the backtrace, specifically verify_pmtmr_rate()'s I/O instructions. It appears to be mach_countup()'s while loop that gets stuck. Booting with "pmtmr=0" works around this for me, as would unsetting CONFIG_X86_PM_TIMER I'd imagine. The hardware I'm doing this on is a bit wonky and I think the hpet is broken on it. Does this look like *really* broken hardware, or something that we should be detecting and able to recover from?