linux-kernel - Re: [RFC PATCH 00/14] Support timezone of ACPI TAD and EFI TIME

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Message-ID: <1387517916.3539.4446.camel@linux-s257.site>
Date:	Fri, 20 Dec 2013 13:38:36 +0800
From:	joeyli <jlee@...e.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Matt Fleming <matt@...sole-pimps.org>,
	Matthew Garrett <matthew.garrett@...ula.com>, Elliott@...com,
	samer.el-haj-mahmoud@...com, Oliver Neukum <oneukum@...e.de>,
	werner@...e.com, trenn@...e.de, JBeulich@...e.com,
	linux-kernel@...r.kernel.org, rtc-linux@...glegroups.com,
	x86@...nel.org,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	linux-acpi@...r.kernel.org, Borislav Petkov <bp@...e.de>
Subject: Re: [RFC PATCH 00/14] Support timezone of ACPI TAD and EFI TIME

於 四，2013-12-19 於 20:22 -0800，H. Peter Anvin 提到：
> On 12/19/2013 08:05 PM, joeyli wrote:
> > 
> > Then that means the priority of PNP0B0x is higher then "CMOS RTC Not
> > Present" flag. ACPI spec doesn't have clear definition on this.
> > 
> 
> According to the Microsoft requirements documents, such a platform is
> broken and shouldn't exist.

OK~~

> 
> > I look forward to Borislav's "EFI runtime mapping" to fix the physical
> > address accessing issue of EFI time service on x86_64 machines. I tested
> > his patches on a issue machine and it works for walk around BIOS bug.
> > 
> > Can we use EFI time services on x86_64 after Borislav's patches accepted
> > to mainline?
> > 
> 
> No.
> 
> 	-hpa

If don't use EFI time, then the first priority is using ACPI TAD if it
present. Due to ACPI TAD is a generic acpi device that's need OS parsing
DSDT table before set system time.

Either move DSDT parser from subsystem initial stage to start_kernel or
move timekeeping initial to after DSDT be parsed. Which one you think is
more possible and risk less? Then I will try that way.


Thanks a lot!
Joey Lee

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