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

[M. Warner Losh]

In message: <200910161400.00564.jkim at FreeBSD.org>
            Jung-uk Kim <jkim at FreeBSD.org> writes:
: 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?

I don't think that's the right solution here.  The pmap_mapdev stuff
should happen when the resource is activated...

Warner