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-rw-r--r--src/northbridge/intel/i945/gma.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/src/northbridge/intel/i945/gma.c b/src/northbridge/intel/i945/gma.c
index 140aaa7cee..e8a57b17c8 100644
--- a/src/northbridge/intel/i945/gma.c
+++ b/src/northbridge/intel/i945/gma.c
@@ -52,11 +52,19 @@
static int gtt_setup(unsigned int mmiobase)
{
unsigned long PGETBL_save;
-
- PGETBL_save = read32(mmiobase + PGETBL_CTL) & ~PGETBL_ENABLED;
+ unsigned long tom; // top of memory
+
+ /*
+ * The Video BIOS places the GTT right below top of memory.
+ *
+ * It is not documented in the Intel 945 datasheet, but the Intel
+ * developers said that it is normally placed there.
+ *
+ * TODO: Add option to make the GTT size runtime configurable
+ */
+ tom = pci_read_config8(dev_find_slot(0, PCI_DEVFN(0, 0)), TOLUD) << 24;
+ PGETBL_save = tom - 256 * KiB;
PGETBL_save |= PGETBL_ENABLED;
-
- PGETBL_save |= pci_read_config32(dev_find_slot(0, PCI_DEVFN(2,0)), 0x5c) & 0xfffff000;
PGETBL_save |= 2; /* set GTT to 256kb */
write32(mmiobase + GFX_FLSH_CNTL, 0);