Re: [PATCH] Longhaul - There are limits

["Rafał Bilski" <rafalbilski@interia.pl>]

>  > It is good idea, but I think there should be check for APIC too, 
>  > but I don't know how to make it. !X86_UP_APIC is for non SMP 
>  > kernels only. It is possible that in this case there will be 
>  > SMP kernel running on single processor with APIC enabled. 
>  > I don't know much about APIC, but as far I know we are poking 
>  > PIC registers direcly and in such case not all interrupts will
>  > be disabled.
> 
> I wonder if this could be solved with something as trivial as..
> 
> 	if (cpu_has_apic)
> 		disable_local_APIC()
> 
> 	...
> 
> 	if (cpu_has_apic)
> 		enable_local_APIC()
> [...]

Wow! But I don't see this symbols exported to modules.
There are functions lapic_suspend / lapic_resume in apic dev 
interface, but do this functions do what we need?

> We should probably also avoid touching the PIC if we're in APIC mode
> with something like..
> 
>     if (pic_mode == 1) {
> 		...
> 		PIC poking goes here..
> 	}
> 
> (Will also need to EXPORT_SYMBOL(pic_mode) from mpparse.c)
> 
> 		Dave
> 

We really need to touch PIC. If we can't then we can't change frequency.

Rafa³


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