RE: [Xen-devel] [PATCH] x86: suppress HPET broadcast initialization in the presence of ARAT

["Wei, Gang" <gang.wei@xxxxxxxxx>]

Jan Beulich wrote on 2011-02-10:
> This follows Linux commit 39fe05e58c5e448601ce46e6b03900d5bf31c4b0,
> noticing that all this setup is pointless when ARAT support is there, 
> and knowing that on SLED11's native kernel it has actually caused S3 resume 
> issues.
> 
> A question would be whether HPET legacy interrupts should be forced 
> off in this case (rather than leaving whatever came from firmware).
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
> 
> --- a/xen/arch/x86/hpet.c
> +++ b/xen/arch/x86/hpet.c
> @@ -557,6 +557,9 @@ void hpet_broadcast_init(void)
>      u32 hpet_id, cfg;
>      int i;
> +    if ( boot_cpu_has(X86_FEATURE_ARAT) )
> +        return;
> +
>      if ( irq_channel == NULL )
>      {
>          irq_channel = xmalloc_array(int, nr_irqs);
>

Although this patch was already checked in, I still have to say it is not 
necessary for Xen. Because hpet_broadcast_init() fn is only called if 
(xen_cpuidle && !boot_cpu_has(X86_FEATURE_ARAT)) in disable_pit_irq(). Of 
course I agree to keep it as a never used double check.

Jimmy



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