AuxXxilium/linux_dsm_epyc7002
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[PATCH] x86_64: Use the e820 hole to map the IOMMU/AGP aperture

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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>
This commit is contained in:
Andi Kleen 2005-04-16 15:25:13 -07:00 committed by Linus Torvalds
parent a1e9778203
commit ece90303ec
1 changed files with 30 additions and 11 deletions
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41
arch/x86_64/kernel/aperture.c
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@ -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 *name, u64 aper_base, u32 aper_size)
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();