Re: Unifying /dev/{mem,kmem,zero,null} implementations

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

On Sun, Feb 24, 2008 at 12:40:51AM +0000, Chris Gilbert wrote:
> The documentation says every pmap_kremove needs a pmap_update, relying on 
> something later on doing a pmap_update is risky.

Not here. The address is used strictly for one purpose and a CPU can
only use it when holding the mutex. So the pmap_update after
pmap_kremove shouldn't be needed.

> In theory pmap_kremove could be optimised to not change anything in 
> hardware, and defer the work to be done till the pmap_update, while I don't 
> believe any platform has gone to that level yet, we shouldn't exclude the 
> possibility by not following the documented API.

I don't read the documentation that way. pmap_update will happen at a
later point anyway and that should be good enough.

I've updated the diff to include the /dev/io support for COMPAT_10 and
COMPAT_FREEBSD and to include the pmap_update after pmap_kenter.

Joerg