Re: [PATCH 2/3] i386: add io_map_cached

[Justus Winter]

Quoting Samuel Thibault (2014-05-15 02:13:13)
> Hello,
> 
> Justus Winter, le Fri 02 May 2014 21:33:01 +0200, a écrit :
> > io_map_cached is like io_map, but reuses the old mapping if it is
> > applicable.
> 
> But AIUI, if it is not applicable, it does not unmap the previous
> mapping, so we lose virtual memory.
> 
> A really transparent io_map_cached seems not really feasible, since you
> never know what the caller will do with the pointer.

Right, I did this b/c I didn't know how to do this properly.

> I'm wondering: why not just use phystokv() in acpi.c instead?

I'm assuming that you meant to say "why not just use phystokv() in
*like in* acpi.c instead?" ?  Because there I do, and it works fine to
locate the rsdpv1 table (whatever that is).  But accessing this
physical address with phystokv() fails b/c it is outside the mapped
range (for me, that was with stock gnumach and the qemu ACPI
implementation).

Justus