Date: Thu, 2 Feb 2006 17:36:40 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Scott Long <scottl@samsco.org> Cc: freebsd-current@www.freebsd.org Subject: Re: mapping "random" physical memory into kernel Message-ID: <17378.35192.656884.935489@grasshopper.cs.duke.edu> In-Reply-To: <43E288B0.6080804@samsco.org> References: <17378.34270.630897.473143@grasshopper.cs.duke.edu> <43E288B0.6080804@samsco.org>
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Scott Long writes: > Andrew Gallatin wrote: > > Can somebody please remind me what the supported way to establish a > > kernel virtual address for a "random" chunk of physical memory is? > > I'm currently using pmap_mapdev() directly, but that just feels > > dirty... > > > > I need to twiddle the settings of an Nvidia NF4 bridge in extended > > PCI config space (offset 0x178). These offsets are not accessible > > via normal pci config space writes, but are doable when you use the > > 0xe000000 mapping. > > Extended pci config space is supported by default on i386, but I > haven't gotten around to figuring out the right strategy for > amd64. I'd like to be able to map the entire 256MB range instead > of the on-demand approach with i386, but I need to learn more about > the various VM maps on amd64 first. Cool. It would be great if it worked; I'd love to remove a bunch of grotty code ;) > > > > The problem is that this memory is not really associated with > > anything, so a normal bus_alloc_resource() allocation doesn't > > seem like it would work. > > pmap_mapdev is the correct interface for this. Except it doesn't appear to exist on sparc64. But I doubt we'd ever see an NF4 bridge there, so I suppose I can ifdef it for i386/amd64. Drew
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