From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Sigler Subject: Re: High resolution timers on ACPI-less kernel Date: Tue, 09 Oct 2007 12:35:29 +0200 Message-ID: <470B5971.40601@free.fr> References: <470B44A1.7080007@free.fr> <1191921343.13628.0.camel@godzilla.tecnorama.it> <470B49BD.4070506@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp4-g19.free.fr ([212.27.42.30]:33160 "EHLO smtp4-g19.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752084AbXJIKfa (ORCPT ); Tue, 9 Oct 2007 06:35:30 -0400 In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Thomas Gleixner Cc: linux-rt-users@vger.kernel.org, linux-acpi@vger.kernel.org Thomas Gleixner wrote: > On Tue, 9 Oct 2007, John Sigler wrote: >> Alessio Igor Bogani wrote: >>> On Tue, 2007-10-09 at 11:06 +0200, John Sigler wrote: >>> >>>> I enabled high resolution timer support and disabled ACPI support. >>> >>> http://www.mail-archive.com/linux-rt-users@vger.kernel.org/msg00375.html >> >> There are other clock sources on my system. >> The timestamp counter is reliable (as far as I can tell). > > See previous mail. > >> The LAPIC timer is reliable. > > LAPIC timer is a clock event device, not a clock source. It can be > used to program the next event, but not to read the time. > >> (I've just disabled the PM timer.) > > Yup, which in turn disables highres. OK. I have two more questions. Can the kernel verify the correctness of the TSC with the PIT? When I enable the ACPI PM timer, the kernel tells me: * The chipset may have PM-Timer Bug. Due to workarounds for a bug, * this clock source is slow. If you are sure your timer does not have * this bug, please use "acpi_pm_good" to disable the workaround How can I tell whether my PM timer has this bug or not? (Specific revision? Test app?) Regards.