sched_lock && thread_lock()

[Marcel Moolenaar]

>> The old patch was missing PowerPC & ia64. Will the final version
>> include those as well?
>
> There are a couple of uses of the global scheduler lock in some  
> architecture specific locations.  They will continue to be safe  
> with the 4BSD scheduler.  I intended to work on these issues with  
> the architecture maintainers after the threadlock patch goes in.   
> Can you suggest some alternative to sched_lock for pmap_switch in  
> ia64?

pmap_switch() is called from cpu_switch() and from pmap_install().
So, currently, pmap_install() grabs sched_lock to mimic the
cpu_switch() path and we assert having sched_lock in pmap_switch().
Basically, any lock that serializes cpu_switch() would work, because
we don't want to switch the thread while in the middle of setting up
the region registers.

> There are a couple of these small issues that should be perfectly  
> safe that I was hoping to address outside of this patch so that it  
> didn't get too big.

I noticed you introduced sched_throw(). Would it harm if ia64
doesn't yet use sched_throw() and instead has the sequence it
replaces? In other words: is the initial implementation of
sched_throw() the same as the current code?

-- 
Marcel Moolenaar
xcllnt at mac.com