[PATCH] x86_64: checking aperture size order

some system is using 32M for gart and agp when memory is less 4G.
kernel will reject and try to allcate another 64M that is not needed.
we will lose 64M ram.

this patch add workaround by checking aper_base/order between NB and agp bridge.
if they are the same, and memory size is than 4G, will let it go.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

Index: linux-2.6/arch/x86/kernel/aperture_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/aperture_64.c
+++ linux-2.6/arch/x86/kernel/aperture_64.c
@@ -83,7 +83,7 @@ static u32 __init allocate_aperture(void
 	return (u32)__pa(p);
 }
 
-static int __init aperture_valid(u64 aper_base, u32 aper_size)
+static int __init aperture_valid(u64 aper_base, u32 aper_size, u32 min_size)
 {
 	if (!aper_base)
 		return 0;
@@ -96,8 +96,9 @@ static int __init aperture_valid(u64 ape
 		printk(KERN_ERR "Aperture pointing to e820 RAM. Ignoring.\n");
 		return 0;
 	}
-	if (aper_size < 64*1024*1024) {
-		printk(KERN_ERR "Aperture too small (%d MB)\n", aper_size>>20);
+	if (aper_size < min_size) {
+		printk(KERN_ERR "Aperture too small (%d MB) than (%d MB)\n",
+				 aper_size>>20, min_size>>20);
 		return 0;
 	}
 
@@ -167,7 +168,9 @@ static __u32 __init read_agp(int num, in
 	 * On some sick chips, APSIZE is 0. It means it wants 4G
 	 * so let double check that order, and lets trust AMD NB settings:
 	 */
-	if (aper + (32UL<<(20 + *order)) > 0x100000000UL) {
+	printk(KERN_INFO "Aperture from AGP @ %Lx old size %u MB\n",
+			aper, 32 << old_order);
+	if (aper + (32ULL<<(20 + *order)) > 0x100000000ULL) {
 		printk(KERN_INFO "Aperture size %u MB (APSIZE %x) is not right, using settings from NB\n",
 				32 << *order, apsizereg);
 		*order = old_order;
@@ -176,7 +179,7 @@ static __u32 __init read_agp(int num, in
 	printk(KERN_INFO "Aperture from AGP @ %Lx size %u MB (APSIZE %x)\n",
 			aper, 32 << *order, apsizereg);
 
-	if (!aperture_valid(aper, (32*1024*1024) << *order))
+	if (!aperture_valid(aper, (32*1024*1024) << *order, 32<<20))
 		return 0;
 	return (u32)aper;
 }
@@ -302,8 +305,8 @@ void __init early_gart_iommu_check(void)
 		fix = 1;
 
 	if (gart_fix_e820 && !fix && aper_enabled) {
-		if (e820_any_mapped(aper_base, aper_base + aper_size,
-				    E820_RAM)) {
+		if (!e820_all_mapped(aper_base, aper_base + aper_size,
+				    E820_RESERVED)) {
 			/* reserved it, so we can resuse it in second kernel */
 			printk(KERN_INFO "update e820 for GART\n");
 			add_memory_region(aper_base, aper_size, E820_RESERVED);
@@ -324,8 +327,11 @@ void __init early_gart_iommu_check(void)
 
 }
 
+static int __initdata printed_gart_size_msg;
+
 void __init gart_iommu_hole_init(void)
 {
+	u32 agp_aper_base = 0, agp_aper_order = 0;
 	u32 aper_size, aper_alloc = 0, aper_order = 0, last_aper_order = 0;
 	u64 aper_base, last_aper_base = 0;
 	int fix, num, valid_agp = 0;
@@ -337,6 +343,9 @@ void __init gart_iommu_hole_init(void)
 
 	printk(KERN_INFO  "Checking aperture...\n");
 
+	if (!fallback_aper_force)
+		agp_aper_base = search_agp_bridge(&agp_aper_order, &valid_agp);
+
 	fix = 0;
 	node = 0;
 	for (num = 24; num < 32; num++) {
@@ -355,9 +364,21 @@ void __init gart_iommu_hole_init(void)
 				node, aper_base, aper_size >> 20);
 		node++;
 
-		if (!aperture_valid(aper_base, aper_size)) {
-			fix = 1;
-			break;
+		if (!aperture_valid(aper_base, aper_size, 64<<20)) {
+			if (valid_agp && agp_aper_base &&
+			    agp_aper_base == aper_base &&
+			    agp_aper_order == aper_order) {
+				/* the same between two setting from NB and agp */
+				if (!no_iommu && end_pfn > MAX_DMA32_PFN && !printed_gart_size_msg) {
+					printk(KERN_ERR "you are using iommu with agp, but GART size is less than 64M\n");
+					printk(KERN_ERR "please increase GART size in your BIOS setup\n");
+					printk(KERN_ERR "if BIOS doesn't have that option, contact your HW vendor!\n");
+					printed_gart_size_msg = 1;
+				}
+			} else {
+				fix = 1;
+				break;
+			}
 		}
 
 		if ((last_aper_order && aper_order != last_aper_order) ||
@@ -378,8 +399,10 @@ void __init gart_iommu_hole_init(void)
 		return;
 	}
 
-	if (!fallback_aper_force)
-		aper_alloc = search_agp_bridge(&aper_order, &valid_agp);
+	if (!fallback_aper_force) {
+		aper_alloc = agp_aper_base;
+		aper_order = agp_aper_order;
+	}
 
 	if (aper_alloc) {
 		/* Got the aperture from the AGP bridge */
Index: linux-2.6/drivers/char/agp/amd64-agp.c
===================================================================
--- linux-2.6.orig/drivers/char/agp/amd64-agp.c
+++ linux-2.6/drivers/char/agp/amd64-agp.c
@@ -245,11 +245,7 @@ static int __devinit aperture_valid(u64 
 		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 
 		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(str
 	 * 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;