linux-kernel - Re: [PATCH v7 12/13] ACPI / init: Invoke early ACPI initialization earlier

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Date:   Thu, 24 Aug 2017 16:05:28 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Dou Liyang <douly.fnst@...fujitsu.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Zheng, Lv" <lv.zheng@...el.com>, tglx@...utronix.de,
        mingo@...nel.org, hpa@...or.com, ebiederm@...ssion.com,
        peterz@...radead.org, izumi.taku@...fujitsu.com,
        tokunaga.keiich@...fujitsu.com, linux-acpi@...r.kernel.org,
        Julian Wollrath <jwollrath@....de>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH v7 12/13] ACPI / init: Invoke early ACPI initialization
 earlier

Hi Liyang,

On 08/24/17 at 11:54am, Dou Liyang wrote:
> > > Test in my own PC(Lenovo M4340).
> > > Ask help for doing regression testing for the bug said in commit
> > > c4e1acbb35e4
> > > ("ACPI / init: Invoke early ACPI initialization later").
> > > 
> > 
> > Now, I can prove this patch doesn't result in the bug[1] which made the
> > fast TSC calibration using PIT failed in a Thinkpad x121e (AMD E-450
> > APU).
> > 
> > The true reason of the bug is enabling ACPI subsystem earlier than
> > using PIT, not the SCI setup. invoking acpi_enable_subsystem() later

Seems redhat mail server was down earlier, I didn't receive new mail in
this thread.  Just curious, do you know why the fast tsc calibration
using PIT will fail if enabling ACPI subsystem earlier than using PIT?

Thanks
Baoquan

> > could fix this bug as Julian tested and said[2].
> > 
> > And, I found that Commit b064a8fa77df (" ACPI / init: Switch over
> > platform to the ACPI mode later") split the ACPI early initialization
> > code into acpi_early_init() and acpi_subsystem_init(). executing
> > acpi_enable_subsystem() at the original early ACPI initialization spot.
> > 
> > The sequence of them shows below:
> > 
> >  start_kernel
> > +---------------+
> > |
> > +--> .......
> > |
> > |    late_time_init()
> > +--> +-------+
> > |
> > +--> .......
> > |
> > |    acpi_early_init()
> > +--> +-------+
> > |
> > +--> .......
> > |
> > |   acpi_subsystem_init()
> > +-> +--------+
> > 
> > We make sure the acpi_subsystem_init() is called later than
> > late_time_init(), the bug will be avoided.
> > 
> > This patch changes the sequence of late_time_init() and
> > acpi_early_init(), doesn't effect acpi_subsystem_init().
> > 
> > So, this patch is OK.
> > 
> > Btw, Thanks very much for Borislav Petkov, he will have access to
> > Thinkpad x121e from Mid-August and will test this series.
> > 
> 
> Almost one month passed, Borislav have tested this series in Thinkpad
> x121e and I also have tested in my box and QEmu again. It is OK.
> 
> BTW,
> 1) I found your commit b064a8fa77df (" ACPI / init: Switch over
> platform to the ACPI mode later") split the ACPI early initialization
> code into acpi_early_init() and acpi_subsystem_init(). Actually enabling
> the ACPI subsystem is in acpi_subsystem_init().
> 
> 2) As we discussed earlier, invoking acpi_put_table() is not good for
> this situation.
> 
> So I do this patch, Is that goot to you? Any comments will be welcome.
> 
> If it is OK, As the patches need to be re-based, and I also found
> several spelling mistake, I will send a new version next week.
> 
> Thanks,
> 	dou.
> 
> > [1] https://lkml.org/lkml/2014/3/10/123
> > [2] https://lkml.org/lkml/2014/3/12/311
> > 
> > 
> > Thanks
> >     dou.
> > 
> > >  init/main.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/init/main.c b/init/main.c
> > > index df58a41..7a09467 100644
> > > --- a/init/main.c
> > > +++ b/init/main.c
> > > @@ -654,12 +654,12 @@ asmlinkage __visible void __init start_kernel(void)
> > >      kmemleak_init();
> > >      setup_per_cpu_pageset();
> > >      numa_policy_init();
> > > +    acpi_early_init();
> > >      if (late_time_init)
> > >          late_time_init();
> > >      calibrate_delay();
> > >      pidmap_init();
> > >      anon_vma_init();
> > > -    acpi_early_init();
> > >  #ifdef CONFIG_X86
> > >      if (efi_enabled(EFI_RUNTIME_SERVICES))
> > >          efi_enter_virtual_mode();
> > > 
> 
>