[PATCH] x86_64: Use the e820 hole to map the IOMMU/AGP aperture
This might save memory on some Opteron systems without AGP bridge. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -33,11 +33,13 @@ int fallback_aper_force __initdata = 0;
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int fix_aperture __initdata = 1;
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/* This code runs before the PCI subsystem is initialized, so just
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access the northbridge directly. */
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#define NB_ID_3 (PCI_VENDOR_ID_AMD | (0x1103<<16))
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static struct resource aper_res = {
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.name = "Aperture",
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.flags = IORESOURCE_MEM,
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};
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static u32 __init allocate_aperture(void)
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{
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#ifdef CONFIG_DISCONTIGMEM
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@ -53,11 +55,24 @@ static u32 __init allocate_aperture(void)
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aper_size = (32 * 1024 * 1024) << fallback_aper_order;
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/*
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* Aperture has to be naturally aligned. This means an 2GB aperture won't
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* have much chances to find a place in the lower 4GB of memory.
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* Unfortunately we cannot move it up because that would make the
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* IOMMU useless.
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* Aperture has to be naturally aligned. This means an 2GB
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* aperture won't have much chances to find a place in the
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* lower 4GB of memory. Unfortunately we cannot move it up
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* because that would make the IOMMU useless.
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*/
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/* First try to find some free unused space */
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if (!allocate_resource(&iomem_resource, &aper_res,
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aper_size,
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0, 0xffffffff,
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aper_size,
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NULL, NULL)) {
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printk(KERN_INFO "Putting aperture at %lx-%lx\n",
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aper_res.start, aper_res.end);
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return aper_res.start;
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}
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/* No free space found. Go on to waste some memory... */
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p = __alloc_bootmem_node(nd0, aper_size, aper_size, 0);
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if (!p || __pa(p)+aper_size > 0xffffffff) {
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printk("Cannot allocate aperture memory hole (%p,%uK)\n",
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@ -66,7 +81,7 @@ static u32 __init allocate_aperture(void)
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free_bootmem_node(nd0, (unsigned long)p, aper_size);
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return 0;
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}
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printk("Mapping aperture over %d KB of RAM @ %lx\n",
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printk("Mapping aperture over %d KB of precious RAM @ %lx\n",
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aper_size >> 10, __pa(p));
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return (u32)__pa(p);
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}
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@ -87,10 +102,16 @@ static int __init aperture_valid(char *name, u64 aper_base, u32 aper_size)
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printk("Aperture from %s pointing to e820 RAM. Ignoring.\n",name);
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return 0;
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}
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/* Don't check the resource here because the aperture is usually
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in an e820 reserved area, and we allocated these earlier. */
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return 1;
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}
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/* Find a PCI capability */
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/*
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* Find a PCI capability.
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* This code runs before the PCI subsystem is initialized, so just
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* access the northbridge directly.
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*/
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static __u32 __init find_cap(int num, int slot, int func, int cap)
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{
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u8 pos;
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@ -255,8 +276,6 @@ void __init iommu_hole_init(void)
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fallback_aper_force) {
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printk("Your BIOS doesn't leave a aperture memory hole\n");
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printk("Please enable the IOMMU option in the BIOS setup\n");
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printk("This costs you %d MB of RAM\n",
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32 << fallback_aper_order);
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aper_order = fallback_aper_order;
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aper_alloc = allocate_aperture();
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