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SubjectRe: [discuss] [21/31] x86_64: Always use CPUID 80000008 to figure out MTRR address space size
We need to use the size_and_mask in set_mtrr_var_ranges(which is called 
while programming MTRR's for AP's

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>

--- linux/arch/i386/kernel/cpu/mtrr/generic.c~ 2005-04-10 14:07:11.821466664 -0700
+++ linux/arch/i386/kernel/cpu/mtrr/generic.c 2005-04-10 14:12:21.913325536 -0700
@@ -192,7 +192,8 @@ static int set_mtrr_var_ranges(unsigned

rdmsr(MTRRphysBase_MSR(index), lo, hi);
if ((vr->base_lo & 0xfffff0ffUL) != (lo & 0xfffff0ffUL)
- || (vr->base_hi & 0xfUL) != (hi & 0xfUL)) {
+ || (vr->base_hi & (size_and_mask >> (32 - PAGE_SHIFT))) !=
+ (hi & (size_and_mask >> (32 - PAGE_SHIFT)))) {
mtrr_wrmsr(MTRRphysBase_MSR(index), vr->base_lo, vr->base_hi);
changed = TRUE;
}
@@ -200,7 +201,8 @@ static int set_mtrr_var_ranges(unsigned
rdmsr(MTRRphysMask_MSR(index), lo, hi);

if ((vr->mask_lo & 0xfffff800UL) != (lo & 0xfffff800UL)
- || (vr->mask_hi & 0xfUL) != (hi & 0xfUL)) {
+ || (vr->mask_hi & (size_and_mask >> (32 - PAGE_SHIFT))) !=
+ (hi & (size_and_mask >> (32 - PAGE_SHIFT)))) {
mtrr_wrmsr(MTRRphysMask_MSR(index), vr->mask_lo, vr->mask_hi);
changed = TRUE;
}
On Thu, Apr 07, 2005 at 05:42:36PM +0200, Andi Kleen wrote:
> Always use CPUID 80000008 to figure out MTRR address space size
>
> It doesn't make sense to only do this only for AMD K8.
>
> This would support future CPUs with extended address spaces properly.
>
> For i386 and x86-64
>
> Cc: davej@redhat.com
>
>
> Index: linux/arch/i386/kernel/cpu/mtrr/main.c
> ===================================================================
> --- linux.orig/arch/i386/kernel/cpu/mtrr/main.c
> +++ linux/arch/i386/kernel/cpu/mtrr/main.c
> @@ -614,40 +614,21 @@ static int __init mtrr_init(void)
> mtrr_if = &generic_mtrr_ops;
> size_or_mask = 0xff000000; /* 36 bits */
> size_and_mask = 0x00f00000;
> -
> - switch (boot_cpu_data.x86_vendor) {
> - case X86_VENDOR_AMD:
> - /* The original Athlon docs said that
> - total addressable memory is 44 bits wide.
> - It was not really clear whether its MTRRs
> - follow this or not. (Read: 44 or 36 bits).
> - However, "x86-64_overview.pdf" explicitly
> - states that "previous implementations support
> - 36 bit MTRRs" and also provides a way to
> - query the width (in bits) of the physical
> - addressable memory on the Hammer family.
> - */
> - if (boot_cpu_data.x86 == 15
> - && (cpuid_eax(0x80000000) >= 0x80000008)) {
> - u32 phys_addr;
> - phys_addr = cpuid_eax(0x80000008) & 0xff;
> - size_or_mask =
> - ~((1 << (phys_addr - PAGE_SHIFT)) - 1);
> - size_and_mask = ~size_or_mask & 0xfff00000;
> - }
> - /* Athlon MTRRs use an Intel-compatible interface for
> - * getting and setting */
> - break;
> - case X86_VENDOR_CENTAUR:
> - if (boot_cpu_data.x86 == 6) {
> - /* VIA Cyrix family have Intel style MTRRs, but don't support PAE */
> - size_or_mask = 0xfff00000; /* 32 bits */
> - size_and_mask = 0;
> - }
> - break;
> -
> - default:
> - break;
> +
> + /* This is an AMD specific MSR, but we assume(hope?) that
> + Intel will implement it to when they extend the address
> + bus of the Xeon. */
> + if (cpuid_eax(0x80000000) >= 0x80000008) {
> + u32 phys_addr;
> + phys_addr = cpuid_eax(0x80000008) & 0xff;
> + size_or_mask = ~((1 << (phys_addr - PAGE_SHIFT)) - 1);
> + size_and_mask = ~size_or_mask & 0xfff00000;
> + } else if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR &&
> + boot_cpu_data.x86 == 6) {
> + /* VIA C* family have Intel style MTRRs, but
> + don't support PAE */
> + size_or_mask = 0xfff00000; /* 32 bits */
> + size_and_mask = 0;
> }
> } else {
> switch (boot_cpu_data.x86_vendor) {
-
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