x86BIOS and the ISA bus and low memory in general...

[Jung-uk Kim]

On Friday 16 October 2009 01:46 pm, Jung-uk Kim wrote:
> On Thursday 15 October 2009 04:37 pm, Marcel Moolenaar wrote:
> > On Oct 15, 2009, at 12:45 PM, M. Warner Losh wrote:
> > > [[ redirected to arch@ ]]
> > >
> > > In message: <200910151431.53236.jkim at FreeBSD.org>
> > >            Jung-uk Kim <jkim at FreeBSD.org> writes:
> > > <snip>
> > >
> > > : This is actually very interesting discussion for me because
> > > : one of
> > >
> > > my
> > >
> > > : pet projects is extending x86bios to support non-PC
> > > : architectures. If anyone is interested, the current source
> > > : tarball is here:
> > > :
> > > : http://people.freebsd.org/~jkim/x86bios-20091015.tar.bz2
> > > :
> > > : Especially, please see the code around #ifdef
> > > : X86BIOS_COMPAT_ARCH. Basically, mapping I/O ports and orm(4)
> > > : is missing.  We don't have
> > >
> > > to
> > >
> > > : implement I/O ports but orm(4) vs. bus_space(9) is critical
> > > : to make it a reality.  Please consider it as a real practical
> > > : example for orm, not just a blackhole driver. :-)
> > >
> > > I thought that most video cards had I/O ports as well as video
> > > RAM that needed to be mapped...  Am I crazy?
> >
> > It depends on the platform. On an Itanium machine I have the
> > VGA frame buffer is at physical address 0xA0000-0xC0000.
>
> The address is the same, then. :-)
>
> > The only requirement is that you use non-cached I/O, otherwise
> > you get a machine check. This can mean a non-identity mapping
> > or not. It all depends...
>
> I couldn't find a way to manipulate memory attribute directly on
> ia64, i.e., mem_range_attr_{get,set}() and pmap_mapdev_attr() only
> exist on amd64 and i386.  Does pmap_mapdev() set the attribute as
> UC?

It seems pmap_mapdev() on ia64 uses IA64_PHYS_TO_RR6() macro.  If I 
read the source correctly, then it is gives UC mapped "view" of the 
physical address, right?  If so, orm(4) can simply do 
pmap_mapdev()/pmap_unmapdev() around bus_space_read_region_1().  Am I 
right?

Jung-uk Kim

> > I/O ports don't exist and there's a memory region for generating
> > I/O port accesses, but the translation is not linear, so you
> > can't work with a single base and port offset to get this to
> > work. See ia64_ioport_address() in sys/ia64/ia64/machdep.c
>
> It seems there are PC-compatible inline functions {in,out}[bwl] in
> sys/ia64/include/cpufunc.h.  Will they work as I expect?
>
> Thanks,
>
> Jung-uk Kim