x86: checking aperture size order

some systems are using 32M for gart and agp when memory is less than 4G.
Kernel will reject and try to allcate another 64M that is not needed,
and we will waste 64M of perfectly good RAM.

this patch adds a workaround by checking aper_base/order between NB and
agp bridge. If they are the same, and memory size is less than 4G, it
will allow it.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/char/agp/amd64-agp.c b/drivers/char/agp/amd64-agp.c
index 9e3939db76e..9c24470a825 100644
--- a/drivers/char/agp/amd64-agp.c
+++ b/drivers/char/agp/amd64-agp.c
@@ -245,11 +245,7 @@ static int __devinit aperture_valid(u64 aper, u32 size)
 		printk(KERN_ERR PFX "No aperture\n");
 		return 0;
 	}
-	if (size < 32*1024*1024) {
-		printk(KERN_ERR PFX "Aperture too small (%d MB)\n", size>>20);
-		return 0;
-	}
-       if ((u64)aper + size > 0x100000000ULL) {
+	if ((u64)aper + size > 0x100000000ULL) {
 		printk(KERN_ERR PFX "Aperture out of bounds\n");
 		return 0;
 	}
@@ -257,6 +253,10 @@ static int __devinit aperture_valid(u64 aper, u32 size)
 		printk(KERN_ERR PFX "Aperture pointing to RAM\n");
 		return 0;
 	}
+	if (size < 32*1024*1024) {
+		printk(KERN_ERR PFX "Aperture too small (%d MB)\n", size>>20);
+		return 0;
+	}
 
 	/* Request the Aperture. This catches cases when someone else
 	   already put a mapping in there - happens with some very broken BIOS
@@ -317,7 +317,7 @@ static __devinit int fix_northbridge(struct pci_dev *nb, struct pci_dev *agp,
 	 * On some sick chips APSIZE is 0. This means it wants 4G
 	 * so let double check that order, and lets trust the AMD NB settings
 	 */
-	if (aper + (32ULL<<(20 + order)) > 0x100000000ULL) {
+	if (order >=0 && aper + (32ULL<<(20 + order)) > 0x100000000ULL) {
 		printk(KERN_INFO "Aperture size %u MB is not right, using settings from NB\n",
 				  32 << order);
 		order = nb_order;