On Sun, 24 Feb 2002, Andrew Gallatin wrote:
>
> I'm not fluent in x86 asm, so can you confirm for me what you're
> attempting to do here?
>
> I think you're making critical_enter()/critical_exit() cheaper by not
> actually messing with the interrupt hardware when they're called.
> Very much like what we do in 4-stable.
>
> Instead, you set/clear a per-cpu flag (or incr/decr a counter). If an
> interrupt comes in when you're inside a critical section, you make
> note of it & mask interrupts on that cpu. In critical_exit(),
> you run the interrupt handler if there's a pending interrupt, and
> unmask interrupts. If there's not a pending interrupt, you just clear
> the flag (or devrement a counter).
>
> Is that basically it?
>
> If so, I'm wondering if this is even possible on alpha, where we don't
> have direct access to the hardware. However, according to the psuedo
> code for rti in the Brown book, munging with the saved PSL in
> trapframe to set the IPL should work. Hmm..
I think we can tweak the saved PSL and it should be able to mask
interrupts in the same way as for x86. This should be quite easy for ia64
too.
--
Doug Rabson Mail: [EMAIL PROTECTED]
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