On Thu, Nov 28, 2013 at 05:15:10PM +0200, ville.syrjala@xxxxxxxxxxxxxxx wrote: > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > There doesn't seem to an explicit stolen memory base register on gen2. > Some old comment in the code suggests we should get it via > max_low_pfn_mapped, but that's clearly a bad idea on my MGM. > > The e820 map in said machine looks like this: > [ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009f7ff] usable > [ 0.000000] BIOS-e820: [mem 0x000000000009f800-0x000000000009ffff] reserved > [ 0.000000] BIOS-e820: [mem 0x00000000000ce000-0x00000000000cffff] reserved > [ 0.000000] BIOS-e820: [mem 0x00000000000dc000-0x00000000000fffff] reserved > [ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000001f6effff] usable > [ 0.000000] BIOS-e820: [mem 0x000000001f6f0000-0x000000001f6f7fff] ACPI data > [ 0.000000] BIOS-e820: [mem 0x000000001f6f8000-0x000000001f6fffff] ACPI NVS > [ 0.000000] BIOS-e820: [mem 0x000000001f700000-0x000000001fffffff] reserved > [ 0.000000] BIOS-e820: [mem 0x00000000fec10000-0x00000000fec1ffff] reserved > [ 0.000000] BIOS-e820: [mem 0x00000000ffb00000-0x00000000ffbfffff] reserved > [ 0.000000] BIOS-e820: [mem 0x00000000fff00000-0x00000000ffffffff] reserved > > That makes max_low_pfn_mapped = 1f6f0000, so assuming our stolen memory > would start there would place it on top of some ACPI memory regions. > So not a good idea as already stated. > > The 9MB region after the ACPI regions at 0x1f700000 however looks > promising given that the macine reports the stolen memory size to be > 8MB. Looking at the PGTBL_CTL register, the GTT entries are at offset > 0x1fee00000, and given that the GTT entries occupy 128KB, it looks like > the stolen memory could start at 0x1f700000 and the GTT entries would > occupy the last 128KB of the stolen memory. I have no idea about the > extra 1MB after the GTT entries. The base address for stolen memory is explicitly Top of Memory on gen2, at least in 830/845 cspecs that I found (and recall). But this idea is interesting... -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
