From: "Andi Kleen" <[email protected]>
This might save memory on some Opteron systems without AGP bridge.
Signed-off-by: Andi Kleen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
25-akpm/arch/x86_64/kernel/aperture.c | 41 ++++++++++++++++++++++++----------
1 files changed, 30 insertions(+), 11 deletions(-)
diff -puN arch/x86_64/kernel/aperture.c~x86_64-use-the-e820-hole-to-map-the-iommu-agp-aperture arch/x86_64/kernel/aperture.c
--- 25/arch/x86_64/kernel/aperture.c~x86_64-use-the-e820-hole-to-map-the-iommu-agp-aperture 2005-04-12 03:21:25.519257384 -0700
+++ 25-akpm/arch/x86_64/kernel/aperture.c 2005-04-12 03:21:25.522256928 -0700
@@ -33,11 +33,13 @@ int fallback_aper_force __initdata = 0;
int fix_aperture __initdata = 1;
-/* This code runs before the PCI subsystem is initialized, so just
- access the northbridge directly. */
-
#define NB_ID_3 (PCI_VENDOR_ID_AMD | (0x1103<<16))
+static struct resource aper_res = {
+ .name = "Aperture",
+ .flags = IORESOURCE_MEM,
+};
+
static u32 __init allocate_aperture(void)
{
#ifdef CONFIG_DISCONTIGMEM
@@ -53,11 +55,24 @@ static u32 __init allocate_aperture(void
aper_size = (32 * 1024 * 1024) << fallback_aper_order;
/*
- * Aperture has to be naturally aligned. This means an 2GB aperture won't
- * have much chances to find a place in the lower 4GB of memory.
- * Unfortunately we cannot move it up because that would make the
- * IOMMU useless.
+ * Aperture has to be naturally aligned. This means an 2GB
+ * aperture won't have much chances to find a place in the
+ * lower 4GB of memory. Unfortunately we cannot move it up
+ * because that would make the IOMMU useless.
*/
+
+ /* First try to find some free unused space */
+ if (!allocate_resource(&iomem_resource, &aper_res,
+ aper_size,
+ 0, 0xffffffff,
+ aper_size,
+ NULL, NULL)) {
+ printk(KERN_INFO "Putting aperture at %lx-%lx\n",
+ aper_res.start, aper_res.end);
+ return aper_res.start;
+ }
+
+ /* No free space found. Go on to waste some memory... */
p = __alloc_bootmem_node(nd0, aper_size, aper_size, 0);
if (!p || __pa(p)+aper_size > 0xffffffff) {
printk("Cannot allocate aperture memory hole (%p,%uK)\n",
@@ -66,7 +81,7 @@ static u32 __init allocate_aperture(void
free_bootmem_node(nd0, (unsigned long)p, aper_size);
return 0;
}
- printk("Mapping aperture over %d KB of RAM @ %lx\n",
+ printk("Mapping aperture over %d KB of precious RAM @ %lx\n",
aper_size >> 10, __pa(p));
return (u32)__pa(p);
}
@@ -87,10 +102,16 @@ static int __init aperture_valid(char *n
printk("Aperture from %s pointing to e820 RAM. Ignoring.\n",name);
return 0;
}
+ /* Don't check the resource here because the aperture is usually
+ in an e820 reserved area, and we allocated these earlier. */
return 1;
}
-/* Find a PCI capability */
+/*
+ * Find a PCI capability.
+ * This code runs before the PCI subsystem is initialized, so just
+ * access the northbridge directly.
+ */
static __u32 __init find_cap(int num, int slot, int func, int cap)
{
u8 pos;
@@ -255,8 +276,6 @@ void __init iommu_hole_init(void)
fallback_aper_force) {
printk("Your BIOS doesn't leave a aperture memory hole\n");
printk("Please enable the IOMMU option in the BIOS setup\n");
- printk("This costs you %d MB of RAM\n",
- 32 << fallback_aper_order);
aper_order = fallback_aper_order;
aper_alloc = allocate_aperture();
_
-
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