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Re: I/O permission control in OSKit-Mach
From: |
Marcus Brinkmann |
Subject: |
Re: I/O permission control in OSKit-Mach |
Date: |
Sat, 8 Dec 2001 23:16:25 +0100 |
User-agent: |
Mutt/1.3.23i |
On Sat, Oct 20, 2001 at 10:42:35PM -0400, Roland McGrath wrote:
> Indeed. I think the best plan is to scrutinize the pmap locking strategy
> and do something similar.
I am looking into this, but it looks quite hard. In fact, it requires an
interrupt to signal the other processors (SMP_IPI_VECTOR == 13 is used for
pmap changes). Is there a free interrupt that can be used? Can we
piggyback on the pmap interrupt without increasing the cost for it?
I have only a vague idea how the pmap interrupt stuff works, the comments in
i386/intel/pmap.c helped. However, they also discouraged me a bit from this
complex solution.
Makes me wonder how Linux behaves, I think that I/O bit mangling is task
based here, but as threads are implemented as tasks, I don't think it works
out there the way we want it to behave for us.
I am inclined to postpone this, and just have a simple lock for the other
races and a #warning for SMP machines, that other cpus will only pick it up
after they are rescheduled.
Thanks,
Marcus
--
`Rhubarb is no Egyptian god.' Debian http://www.debian.org brinkmd@debian.org
Marcus Brinkmann GNU http://www.gnu.org marcus@gnu.org
Marcus.Brinkmann@ruhr-uni-bochum.de
http://www.marcus-brinkmann.de
- Re: I/O permission control in OSKit-Mach,
Marcus Brinkmann <=