src/patches/suse-2.6.27.25/patches.arch/x86_agpgart-g33-stoeln-fix-2.patch

   1 From: Brandon Philips <bphilips@suse.de>
   2 Subject: Avoid oops on G33 in 1MB stolen Mem case
   3 References: bnc#391261
   4 Patch-Mainline: soon (see bug for ref)
   5
   6 This is similar to f443675affe3f16dd428e46f0f7fd3f4d703eeab which was
   7 reverted because it broke with older XOrg driver. This patch only fixes
   8 the 1MB stolen case since it causes an oops due to a calculation
   9 problem.
  10
  11 This will not work with older X drivers without the accompanying patch
  12 but I think avoiding an oops and making it possible to work with an
  13 up-to-date xorg driver is reasonable.
  14
  15 Explanation of the oops:
  16
  17 > static void intel_i830_init_gtt_entries(void)
  18 ...
  19 >         } else if (IS_G33) {
  20 >         /* G33's GTT size defined in gmch_ctrl */
  21 >                 switch (gmch_ctrl & G33_PGETBL_SIZE_MASK) {
  22 >                 case G33_PGETBL_SIZE_1M:
  23 >                         size = 1024;
  24 >                         break;
  25 ...
  26 >                 size += 4;
  27
  28 size = 1028
  29
  30 Then since we have the BIOS setting 1MB for the device in the GMCH
  31 control we get to here:
  32
  33 >         } else {
  34 >                 switch (gmch_ctrl & I855_GMCH_GMS_MASK) {
  35 >                 case I855_GMCH_GMS_STOLEN_1M:
  36 >                         gtt_entries = MB(1) - KB(size);
  37 >                         break;
  38
  39 MB(1) = 1 * 1024 * 1024
  40 KB(1028) = 1028 * 1024
  41
  42 MB(1) - KB(1028) = -4096
  43
  44 >         gtt_entries /= KB(4);
  45 >         intel_private.gtt_entries = gtt_entries;
  46
  47 We end up with -1 in gtt_entries.
  48
  49 This leads to intel_i915_configure reading/writing to areas outside of
  50 mapped memory and the oops.
  51
  52 Signed-off-by: Brandon Philips <bphilips@suse.de>
  53 Acked-by: Thomas Renninger <trenn@suse.de>
  54
  55 ---
  56  drivers/char/agp/intel-agp.c |    7 +++++++
  57  1 file changed, 7 insertions(+)
  58
  59 --- a/drivers/char/agp/intel-agp.c
  60 +++ b/drivers/char/agp/intel-agp.c
  61 @@ -564,6 +564,13 @@ static void intel_i830_init_gtt_entries(
  62         } else {
  63                 switch (gmch_ctrl & I855_GMCH_GMS_MASK) {
  64                 case I855_GMCH_GMS_STOLEN_1M:
  65 +                       if (IS_G33) {
  66 +                               size = 0;
  67 +                               printk(KERN_WARNING PFX
  68 +                                      "Warning: G33 chipset with 1MB"
  69 +                                       " allocated. Older X.org Intel drivers"
  70 +                                       " will not work.\n");
  71 +                       }
  72                         gtt_entries = MB(1) - KB(size);
  73                         break;
  74                 case I855_GMCH_GMS_STOLEN_4M: