Re: TSS switching

[Roland McGrath]

> I guess we will drop the automatic io access entirely?  

Yes, I think it was always a stupid feature.

> Can I/O permission violations be catched in userspace, by emulating the
> io_emulate exception?  Then I guess we can just let the default
> implementation return an error anyway.

I'm not really sure what you are asking here.

> We have a global lock for all the iopb mess.  Actually, I think after
> removing all the user space TSS and IO port list stuff, it's only the
> device<->io_port_t lookup, the task bitmap and the ktss manipulation that
> needs to be locked (the ktss manipulation when updating the current tasks
> permissions, not when being in a task switch).  I am right now using the
> global lock exclusively, though.

gnumach is never going to have SMP support anyway, so it's all moot (and
the macros you are using expand to empty).  In oskit-mach, I think we
should get rid of the lookup table and just hang the data directly off the
device_t.