From dri-devel Sat Mar 05 17:42:23 2005 From: Jesse Barnes Date: Sat, 05 Mar 2005 17:42:23 +0000 To: dri-devel Subject: Re: "no scatter/gather memory" ? Message-Id: <200503050942.23605.jbarnes () sgi ! com> X-MARC-Message: https://marc.info/?l=dri-devel&m=111004658428871 On Friday, March 04, 2005 6:01 pm, Roland Scheidegger wrote: > Paul Mackerras wrote: > > Note that that check is also wrong for ppc64. I think it is going to > > be wrong for most 64-bit platforms, since it is assuming that you can > > never have ram at a higher physical address than any I/O devices. On > > 64-bit platforms it is quite common to have some ram and some I/O > > below 4GB, and some more ram above 4GB. > > > > I don't see why we need the check anyway, unless some architecture > > (x86?) will actually panic if you try to ioremap a physical address > > that is below virt_to_phys(high_memory) or something. > > Wouldn't this check even break on x86 with PAE? Those boxes certainly > have parts of their ram mapped above io memory too. Or does that > high_memory variable stay below 4GB with PAE? I think the start of high memory will stay below 4G, but the check should probably be removed anyway. If we really want to make sure that a given offset is in I/O space, we should check that explicitly, and not rely on some 'top of real memory' type variable, since that's inherently non-portable. Jesse ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel