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Date: Fri, 6 Jul 2012 15:02:28 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: Jan Beulich <JBeulich@...e.com>
Cc: mingo@...e.hu, tglx@...utronix.de, hpa@...or.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: simplify mtrr_bp_init()
On Fri, Jul 6, 2012 at 7:18 AM, Jan Beulich <JBeulich@...e.com> wrote:
> Now that the x86_phys_bits cpuinfo field is uniformly available on
> 32- and 64-bit, the function no longer needs to determine this anew.
>
> Additionally, both size_or_mask and size_and_mask can be set once at
> the end of the function instead of individually in each special case,
> as their value solely depends on the physical address size determined
> to be used here.
>
> Signed-off-by: Jan Beulich <jbeulich@...e.com>
>
> ---
> arch/x86/kernel/cpu/mtrr/main.c | 47 ++++++++++------------------------------
> 1 file changed, 12 insertions(+), 35 deletions(-)
>
> --- 3.5-rc5/arch/x86/kernel/cpu/mtrr/main.c
> +++ 3.5-rc5-x86-mtrr-init-simplify/arch/x86/kernel/cpu/mtrr/main.c
> @@ -592,67 +592,41 @@ int __initdata changed_by_mtrr_cleanup;
> */
> void __init mtrr_bp_init(void)
> {
> - u32 phys_addr;
> + unsigned int phys_addr = boot_cpu_data.x86_phys_bits;
>
> init_ifs();
>
> - phys_addr = 32;
> -
> if (cpu_has_mtrr) {
> mtrr_if = &generic_mtrr_ops;
> - size_or_mask = 0xff000000; /* 36 bits */
> - size_and_mask = 0x00f00000;
> - phys_addr = 36;
> -
> - /*
> - * 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) {
> - phys_addr = cpuid_eax(0x80000008) & 0xff;
> - /* CPUID workaround for Intel 0F33/0F34 CPU */
> - if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
> - boot_cpu_data.x86 == 0xF &&
> - boot_cpu_data.x86_model == 0x3 &&
> - (boot_cpu_data.x86_mask == 0x3 ||
> - boot_cpu_data.x86_mask == 0x4))
> - phys_addr = 36;
> -
> - size_or_mask = ~((1ULL << (phys_addr - PAGE_SHIFT)) - 1);
> - size_and_mask = ~size_or_mask & 0xfffff00000ULL;
> - } else if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR &&
> - boot_cpu_data.x86 == 6) {
> +
> + 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;
> phys_addr = 32;
> - }
> + } else if (phys_addr < 36)
> + phys_addr = 36;
> } else {
> switch (boot_cpu_data.x86_vendor) {
> case X86_VENDOR_AMD:
> if (cpu_has_k6_mtrr) {
> /* Pre-Athlon (K6) AMD CPU MTRRs */
> mtrr_if = mtrr_ops[X86_VENDOR_AMD];
> - size_or_mask = 0xfff00000; /* 32 bits */
> - size_and_mask = 0;
> + phys_addr = 32;
> }
> break;
> case X86_VENDOR_CENTAUR:
> if (cpu_has_centaur_mcr) {
> mtrr_if = mtrr_ops[X86_VENDOR_CENTAUR];
> - size_or_mask = 0xfff00000; /* 32 bits */
> - size_and_mask = 0;
> + phys_addr = 32;
> }
> break;
> case X86_VENDOR_CYRIX:
> if (cpu_has_cyrix_arr) {
> mtrr_if = mtrr_ops[X86_VENDOR_CYRIX];
> - size_or_mask = 0xfff00000; /* 32 bits */
> - size_and_mask = 0;
> + phys_addr = 32;
should drop all phys_addr assignment in this function.
x86_phys_bits should have all correct value?
Yinghai
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