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Subject: Re: [RFC PATCH 00/14] Support timezone of ACPI TAD and EFI TIME
From: joeyli <jlee@suse.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
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Date: Sat, 21 Dec 2013 10:43:25 +0800
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於 五，2013-12-20 於 22:45 +0100，Rafael J. Wysocki 提到：
> On Friday, December 20, 2013 01:10:26 PM H. Peter Anvin wrote:
> > On 12/19/2013 09:38 PM, joeyli wrote:
> > > 
> > > 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.
> > > 
> > 
> > I discussed the DSDT/SSDT parsing issue with Rafael and he claims it
> > would require a lot of restructuring.  Unfortunately ACPI is at this
> > point done rather late, as I understand.  All of this is a big problem.
> 
> My understanding, however, is that to use the TAD, we don't actually need to
> create a struct acpi_device for it.  We just need a handle to the ACPICA
> object which can be found using acpi_get_devices() as soon as the namespace
> has been extracted from the DSDT and friends.  That in turn happens in
> acpi_early_init(), which is called from start_kernel() right before
> efi_late_init().
> 
> Is that early enough?
> 
> Rafael
> 

Thanks for your good suggestion, then I have a direction on using ACPI
TAD earlier.

Joey Lee