From mboxrd@z Thu Jan 1 00:00:00 1970 From: Huang Ying Subject: Re: [PATCH] ACPI, APEI, Add APEI _OSC support Date: Thu, 16 Jun 2011 09:55:58 +0800 Message-ID: <4DF962AE.60204@intel.com> References: <1306303538-30524-1-git-send-email-ying.huang@intel.com> <20110614145246.GA17469@srcf.ucam.org> <4DF82CBC.5070400@intel.com> <20110615121703.GA8638@srcf.ucam.org> <4DF950EB.7050400@intel.com> <20110616013812.GA32494@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mga02.intel.com ([134.134.136.20]:31276 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753803Ab1FPB4B (ORCPT ); Wed, 15 Jun 2011 21:56:01 -0400 In-Reply-To: <20110616013812.GA32494@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett Cc: Len Brown , "linux-kernel@vger.kernel.org" , Andi Kleen , "Luck, Tony" , "linux-acpi@vger.kernel.org" On 06/16/2011 09:38 AM, Matthew Garrett wrote: > On Thu, Jun 16, 2011 at 08:40:11AM +0800, Huang Ying wrote: >> On 06/15/2011 08:17 PM, Matthew Garrett wrote: >>>> You means the "APEI Support" bit for standard UUID? Do you know which >>>> machine uses this bit? I can write the code, but I have no machine to >>>> test it. >>> >>> I have access to a Dell system that uses this. >> >> Great! Can you help us to test the code? > > Yup, no problem. > >>> Urgh. One machine I've looked at enables APEI if the WHEA _OSC call is >>> made, and then clears a flag if any other _OSC call is made. In that >>> specific case it doesn't seem to matter (the flag never actually gets >>> checked in any of the other codepaths), but it seems that the intention >>> is for the generic call to be made and the WHEA one to be made after >>> that. >> >> Yes. The WHEA call should be made after the generic one. Another >> situation is as follow: >> >> - Generic _OSC call without "APEI Support" bit is called (in >> acpi_bus_osc_support). >> >> - After some time, when we think it is good to turn on firmware first >> mode fully, usually after we checking HEST and initializing >> corresponding module, we make generic _OSC call with "APEI Support" bit >> to turn on firmware first mode fully in standard way. >> >> Is it a good idea to make generic _OSC call twice, one without "APEI >> Support" bit, the other with "APEI Support" bit? > > I think we probably need to make the HEST decision early, and use that > to decide how to make the generic call. Our experience has been that > many firmware vendors only expect _OSC to be called once with any given > UUID - multiple calls can result in unexpected behaviour. acpi_bus_osc_support is called via subsys_initcall. It is a little hard to do all checking before that. Is it possible to call acpi_bus_osc_support later? Best Regards, Huang Ying