Merging 64 bit changes to -HEAD - part 2

[Neel Natu]

Hi Juli,

On Sat, Jun 19, 2010 at 3:18 AM, Juli Mallett <jmallett at freebsd.org> wrote:
> On Fri, Jun 18, 2010 at 12:41, Neel Natu <neelnatu at gmail.com> wrote:
>> Hi JC,
>>
>> But what you really want here is to eliminate the intr_disable() and
>> intr_restore() and keep sched_pin() and  sched_unpin().
>
> Are you sure?  I'm not.  By disabling interrupts we only have to
> ensure that the fault path on any address we might access within those
> routines doesn't need to use the large memory map.  This isn't
> trivial, but I think we can acquire a reasonable confidence about it.
> If we merely pin, we have to ensure that nothing else that can run
> (including interrupts and threads that run via preemption) that would
> access the large memory map — given that this includes routines like
> pmap_zero_page, I think there's good reason for caution.  Disabling
> interrupts is more conservative, but I think rightly-so.  I may be
> mistaken.
>

Duh. You are right, of course. Sorry for the noise.

best
Neel

> Thanks,
> Juli.
>