svn commit: r202889 - head/sys/kern

[Marius Strobl]

On Sat, Jan 30, 2010 at 04:22:47PM +0100, Attilio Rao wrote:
> 2010/1/30 Marius Strobl <marius at alchemy.franken.de>:
> >
> > I think the idea behind using sched_lock in the sparc64 code is
> > to piggyback on it for protecting the pmap and take advantage of
> > the fact that it's held across cpu_switch() anyway. If that's
> > correct it should be possible to replace it with a separate
> > spinlock dedicated to protecting the pmap or given that due to
> > the macro madness involved in mtx_{,un}lock_spin() it's hard to
> > properly call these from asm by calling spinlock_{enter,exit}()
> > directly.
> 
> Even if that is the case there is no reason to not call
> thread_lock()/thread_unlock() (which will acquire the correct
> sched_lock or do the handover in the sched_4bsd in the right way) and
> keep an unified spinlock in order to keep cpu_switch() simple and
> still offering pmap protection over context switches.
> 

It's not clear to me what threads to use in order to get this
to work the right way, for pmap_release() I'd use curthread and
for pmap_activate() I'd just pass td on to thread_{,un}lock()?
Whould the general approach of using thread_{,un}lock() for pmap
protection also do the right thing in case of ULE?

Marius