Re: [PATCH] x86_64: avoid sending LOCAL_TIMER_VECTOR IPI to itself

[Ingo Molnar]

* Ray Lee <ray-lk@xxxxxxxxxxxxx> wrote:

> Subject: [PATCH] x86_64: avoid sending LOCAL_TIMER_VECTOR IPI to 
> itself
> 
> Ray Lee reported, that on an UP kernel with "noapic" command line 
> option set, the box locks hard during boot.

i think this bug deserves a bit more attention, because similar problems 
could be in other codepaths too.

the problem here is that we tried to send an IPI to ourselves - which 
confused Ray's system which has an IO-APIC, but where due to noapic we 
keep the IO-APIC in its BIOS default.

this isnt a new problem: the new time code just exposed it more 
prominently that it was visible before. (the SMP kernel probably would 
hang in a similar way on Ray's system)

i dont see any clear debugging in the IPI code that excludes self-IPIs. 
I think the only valid way to do that is to use DEST_SELF. Andi?

	Ingo
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