linux-kernel - Re: [PATCH 1/3] rtc-efi: register rtc-efi device when EFI enabled

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Date:	Fri, 28 Dec 2012 17:07:37 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	joeyli <jlee@...e.com>
CC:	Matthew Garrett <matthew.garrett@...ula.com>,
	"matt.fleming@...el.com" <matt.fleming@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Jan Beulich <JBeulich@...e.com>
Subject: Re: [PATCH 1/3] rtc-efi: register rtc-efi device when EFI enabled

On 12/28/2012 05:00 PM, joeyli wrote:
> 於 五，2012-12-28 於 17:43 +0000，Matthew Garrett 提到：
>> On Sat, 2012-12-29 at 00:26 +0800, Lee, Chun-Yi wrote:
>>> UEFI time services, GetTime(), SetTime(), GetWakeupTime(), SetWakeupTime() are also
>>> supported by other non-IA64 architecutre with UEFI BIOS, e.g. x86.
>>>
>>> This patch changed RTC_DRV_EFI configuration to depend on EFI but not just IA64. It
>>> checks efi_enabled flag and efi-rtc driver should enabled.
>>
>> In theory, certainly - but do we still have machines that explode if the
>> get_time call is made? We may also want to think about disabling the
>> legacy access to the RTC if the EFI calls are present.
> 
> The legacy get_time access on my test machine is work fine, not thing
> explode. :-)
> Just we have a function want to expose the timezone information to
> userspace and also store it.
> 

We should indeed save the timezone information if it is available --
either from the ACPI TAD or from the EFI RTC, or even via some
platform-dependent mechanism.  It is important, though, that that is
separate from the order of priority.

	-hpa

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