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

Doug Rabson                             Mail:  [EMAIL PROTECTED]
                                        Phone: +44 20 8348 6160

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