On Thu, 2008-06-05 at 13:35 +0800, Len Brown wrote: > > > On Thu, 5 Jun 2008, Zhao Yakui wrote: > > > Subject: ACPI: Disable the C2C3_FFH access mode if MWAIT is > unsupported > > From: Zhao Yakui <yakui.zhao@xxxxxxxxx> > > > > After the following commit is merged, C2C3_FFH mode will be > enabled and > > passed into the _PDC object. But because MWAIT is unsupported on > some laptops, > > the different power states will be returned by the _CST object. > > Maybe it will be better to disable C2C3_FFH access mode if MWAIT is > unsupported. > > > > commit 991528d7348667924176f3e29addea0675298944 > > Author: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx> > > Date: Mon Sep 25 16:28:13 2006 -0700 > > > > ACPI: Processor native C-states using MWAIT > > > http://bugzilla.kernel.org/show_bug.cgi?id=10807 > > Interesting bug report. > Unfortunately, it is a BIOS bug that the BIOS exposes C3 > when the OS doesn't support MWAIT, but neglects to expose > C3 when the OS does support MWAIT. > > This patch will have no effect on the system in the bug report. > Indeed, it would benefit only a system with a BIOS that thinks > it has MWAIT support but a CPU that thinks it doesn't... > > probably good hygine to do this, but I don't think it will > help anything. > > I think the fix for the machine in bug 10807 is to > have a bootparam that disables mwait support, > say "idle=!mwait" and a DMI entry for that box > that invokes it to work around the BIOS bug. The patch isn't related to the bug, but we got the idea when debugging the bug. Yakui should write a new description which doesn't mention the bugzilla. I thought we need this patch to avoid buggy BIOS. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
