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Date: Fri, 16 Oct 2009 13:25:31 -0600 (MDT)
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To: jkim@FreeBSD.org
From: "M. Warner Losh" <imp@bsdimp.com>
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Cc: xcllnt@mac.com, freebsd-arch@FreeBSD.org
Subject: Re: x86BIOS and the ISA bus and low memory in general...
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In message: <200910161504.09685.jkim@FreeBSD.org>
            Jung-uk Kim <jkim@FreeBSD.org> writes:
: On Friday 16 October 2009 02:25 pm, M. Warner Losh wrote:
: > In message: <200910161400.00564.jkim@FreeBSD.org>
: >
: >             Jung-uk Kim <jkim@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@FreeBSD.org>
: > : > > >            Jung-uk Kim <jkim@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...
: 
: For that, I guess we need another resource flag, e.g., RF_DEVICE, 
: maybe?

No.  The activate will be able to do this.  If we need to, we can move
the activate from MI to MD.

Warner