* Fenghua Yu <fenghua...@intel.com> wrote:
> From: Fenghua Yu <fenghua...@intel.com>
>
> Since erratum AVR31 in "Intel Atom Processor C2000 Product Family
> Specification Update" is published, I add a justification comment for
> disabling IO APIC before Local APIC (commit 522e6646).
>
> Signed-off-by: Fenghua Yu <fenghua...@intel.com>
> ---
> arch/x86/kernel/reboot.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
> index da3c599..c752cb4 100644
> --- a/arch/x86/kernel/reboot.c
> +++ b/arch/x86/kernel/reboot.c
> @@ -558,6 +558,17 @@ void native_machine_shutdown(void)
> {
> /* Stop the cpus and apics */
> #ifdef CONFIG_X86_IO_APIC
> + /*
> + * Disabling IO APIC before local APIC is a workaround for
> + * erratum AVR31 in "Intel Atom Processor C2000 Product Family
> + * Specification Update". In this situation, interrupts that target
> + * a Logical Processor whose Local APIC is either in the process of
> + * being hardware disabled or software disabled are neither delivered
> + * nor discarded. When this erratum occurs, the processor may hang.
> + *
> + * Even without the erratum, it still makes sense to quiet IO APIC
> + * before disabling Local APIC.
> + */
> disable_IO_APIC();
> #endif
Looks good to me, except that patch titles should start with verbs,
i.e. something like:
x86/apic/doc: Add justification for disabling IO APIC before Local APIC
Which makes for a much more fluid reading of shortlogs etc.
Unless you sentences without verbs.
^-------------------------------------------like
;-)
Thanks,
Ingo
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