於 三，2014-03-12 於 12:20 +0100，Rafael J. Wysocki 提到： > On Wednesday, March 12, 2014 12:00:07 PM joeyli wrote: > > Hi Julian, [...] > > > > > > >From 8ef4fff76dd2f50bef1e8eb9c96f3b0228a38401 Mon Sep 17 00:00:00 2001 > > From: Lee, Chun-Yi <j...@suse.com> > > Date: Wed, 12 Mar 2014 11:36:32 +0800 > > Subject: [PATCH] ACPI / init: Run acpi_early_init() before > > timekeeping_init() when CMOS RTC Not Present bit set > > > > This is a variant patch from Rafael J. Wysocki's > > ACPI / init: Run acpi_early_init() before efi_enter_virtual_mode() > > > > According to Matt Fleming, if acpi_early_init() was executed before > > efi_enter_virtual_mode(), the EFI initialization could benefit from > > it, so Rafael's patch makes that happen. > > > > And, later we want accessing ACPI TAD device to set system clock, so > > move acpi_early_init() before timekeeping_init() when "CMOS RTC Not > > Present" bit set. This position is also before efi_enter_virtual_mode(). > > > > Signed-off-by: Lee, Chun-Yi <j...@suse.com> > > --- > > init/main.c | 7 ++++++- > > 1 files changed, 6 insertions(+), 1 deletions(-) > > > > diff --git a/init/main.c b/init/main.c > > index eb03090..e1b69d2 100644 > > --- a/init/main.c > > +++ b/init/main.c > > @@ -561,7 +561,9 @@ asmlinkage void __init start_kernel(void) > > init_timers(); > > hrtimers_init(); > > softirq_init(); > > - acpi_early_init(); > > + if (acpi_gbl_FADT.header.revision >= 5 && > > + acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) > > + acpi_early_init(); > > Sorry, this is not the right way to address that. > > First of all, checking fields in acpi_gbl_FADT from anything in init/main.c > is wrong. If anything, please move that check to acpi_early_init(). And > make it check it if it's been called already. >
I see, thanks for your suggestion. > > timekeeping_init(); > > time_init(); > > sched_clock_postinit(); > > @@ -613,6 +615,9 @@ asmlinkage void __init start_kernel(void) > > calibrate_delay(); > > pidmap_init(); > > anon_vma_init(); > > + if (!(acpi_gbl_FADT.header.revision >= 5 && > > + acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC)) > > + acpi_early_init(); > > And then you can call it here again. > > > #ifdef CONFIG_X86 > > if (efi_enabled(EFI_RUNTIME_SERVICES)) > > efi_enter_virtual_mode(); > > > > But I wonder: Can we simply enable SCI later? In other words, can we > split acpi_early_init() so that the part before acpi_enable_subsystem() > is done before timekeeping_init() and the part including and after > is done right after anon_vma_init()? Would the TAD initialization work > then? > The machine that support ACPI TAD doesn't on my hand now, I need find a time go to check it. Per DSDT, it trigger SMI in _GRT and _SRT to get/set time. Looks no SCI involve. Thanks a lot! Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
