Date: Thu, 15 Oct 2009 13:37:02 -0700 From: Marcel Moolenaar <xcllnt@mac.com> To: "M. Warner Losh" <imp@bsdimp.com> Cc: arch@freebsd.org, jkim@freebsd.org Subject: Re: x86BIOS and the ISA bus and low memory in general... Message-ID: <4890688A-D2DB-431C-ADB6-03A39A8FD10E@mac.com> In-Reply-To: <20091015.134532.-1110324186.imp@bsdimp.com> References: <20091015.085910.-520412456.imp@bsdimp.com> <200910151118.50619.jhb@freebsd.org> <200910151431.53236.jkim@FreeBSD.org> <20091015.134532.-1110324186.imp@bsdimp.com>
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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 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/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 -- Marcel Moolenaar xcllnt@mac.com
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