From mboxrd@z Thu Jan 1 00:00:00 1970 From: Huang Ying Subject: Re: [PATCH] ACPI, APEI, Add APEI _OSC support Date: Wed, 15 Jun 2011 11:53:32 +0800 Message-ID: <4DF82CBC.5070400@intel.com> References: <1306303538-30524-1-git-send-email-ying.huang@intel.com> <20110614145246.GA17469@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]:63166 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754245Ab1FODxq (ORCPT ); Tue, 14 Jun 2011 23:53:46 -0400 In-Reply-To: <20110614145246.GA17469@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" Hi, Matthew, On 06/14/2011 10:52 PM, Matthew Garrett wrote: > On Wed, May 25, 2011 at 02:05:38PM +0800, Huang Ying wrote: > >> To gain full APEI power on these machines, a special APEI _OSC needs >> to be evaluated to tell firmware that Linux has full APEI support. >> This patch add the APEI _OSC support. > > (snip) > >> + static DEFINE_MUTEX(mutex); >> + static int status = APEI_OSC_SETUP_UNKNOWN; >> + static u8 apei_uuid_str[] = "ed855e0c-6c90-47bf-a62a-26de0fc5ad5c"; > > This is the WHEA UUID, right? Yes. >> + u32 capbuf[3]; >> + struct acpi_osc_context context = { >> + .uuid_str = apei_uuid_str, >> + .rev = 1, >> + .cap.length = sizeof(capbuf), >> + .cap.pointer = capbuf, >> + }; >> + >> + mutex_lock(&mutex); >> + if (status == APEI_OSC_SETUP_UNKNOWN) { >> + capbuf[OSC_QUERY_TYPE] = OSC_QUERY_ENABLE; >> + capbuf[OSC_SUPPORT_TYPE] = 0; >> + capbuf[OSC_CONTROL_TYPE] = 0; >> + >> + if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle)) >> + || ACPI_FAILURE(acpi_run_osc(handle, &context))) { >> + pr_err(APEI_PFX "APEI _OSC failed!\n"); >> + status = APEI_OSC_SETUP_FAILED; >> + } else { >> + kfree(context.ret.pointer); >> + status = APEI_OSC_SETUP_SUCCEEDED; >> + } >> + } >> + mutex_unlock(&mutex); >> + >> + return status == APEI_OSC_SETUP_SUCCEEDED ? 0 : -EIO; > > So we fail if the platform doesn't implement WHEA... > >> + rc = apei_osc_setup(); >> + if (rc) { >> + ghes_remove(ghes_dev); >> + return rc; >> + } >> + > > And then tear down GHES. This seems wrong. A platform could predicate > APEI functionality on the ACPI spec APEI indication (which we currently > don't pass) without implementing WHEA, but with this patch we'd refuse > to enable GHES support? We should probably try both the standard method > and the WHEA method and only disable GHES if both fail. 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. BTW, it is better for us to enable APEI firmware first mode (that is, what is enabled by evaluating the WHEA UUID) after GHES reporting is ready (that is, after GHES module is successfully loaded). That is later than current ACPI _OSC evaluation with standard UUID. Is it possible to evaluate _OSC with standard UUID twice? So that we can enable APEI firmware first mode later. > (Also, are there any other sideeffects of indicating that we support > WHEA?) After evaluating _OSC with this UUID, firmware will produce error record to OS, otherwise only unknown NMI. Best Regards, Huang Ying