Date: Fri, 16 Oct 2009 15:17:35 -0400 From: Jung-uk Kim <jkim@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: Marcel Moolenaar <xcllnt@mac.com>, freebsd-arch@freebsd.org Subject: Re: x86BIOS and the ISA bus and low memory in general... Message-ID: <200910161517.37518.jkim@FreeBSD.org> In-Reply-To: <200910161419.08369.jhb@freebsd.org> References: <20091015.085910.-520412456.imp@bsdimp.com> <200910161400.00564.jkim@FreeBSD.org> <200910161419.08369.jhb@freebsd.org>
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On Friday 16 October 2009 02:19 pm, John Baldwin wrote: > On Friday 16 October 2009 1:59:58 pm Jung-uk Kim wrote: > > 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 think you need to back up a bit. Instead of having a bunch of MD > code to provide ISA access for each arch, instead do what Warner > suggests which is to create a psuedo ISA device that attaches to > isa0 and acts as a proxy for ISA I/O. It can allocate ISA > resources for both memory and I/O access and then use bus_space_*() > accesses to perform actual I/O. This will be MI. The only problem > I can see with this approach is if a BIOS call attempts to frob a > resource that another ISA device already owns. There may be ways > around that though. That's very interesting idea and it may be very useful for paravirtualized environment, I guess. However, it's beyond my free time. :-( Just in case, I updated the source and uploaded it here: http://people.freebsd.org/~jkim/x86bios-20091016.tar.bz2 For the efficiency reasons, I'd like to keep the amd64/i386 code as is. Feel free to fill in the MI implementation if you want. Thanks, Jung-uk Kim
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