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/*
* Routines to indentify additional cpu features that are scattered in
* cpuid space.
*/
#include <linux/cpu.h>
#include <asm/pat.h>
#include <asm/processor.h>
struct cpuid_bit {
u16 feature;
u8 reg;
u8 bit;
u32 level;
};
enum cpuid_regs {
CR_EAX = 0,
CR_ECX,
CR_EDX,
CR_EBX
};
void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c)
{
u32 max_level;
u32 regs[4];
const struct cpuid_bit *cb;
static const struct cpuid_bit cpuid_bits[] = {
{ X86_FEATURE_IDA, CR_EAX, 1, 0x00000006 },
{ 0, 0, 0, 0 }
};
for (cb = cpuid_bits; cb->feature; cb++) {
/* Verify that the level is valid */
max_level = cpuid_eax(cb->level & 0xffff0000);
if (max_level < cb->level ||
max_level > (cb->level | 0xffff))
continue;
cpuid(cb->level, ®s[CR_EAX], ®s[CR_EBX],
®s[CR_ECX], ®s[CR_EDX]);
if (regs[cb->reg] & (1 << cb->bit))
set_cpu_cap(c, cb->feature);
}
}
#ifdef CONFIG_X86_PAT
void __cpuinit validate_pat_support(struct cpuinfo_x86 *c)
{
if (!cpu_has_pat)
pat_disable("PAT not supported by CPU.");
switch (c->x86_vendor) {
case X86_VENDOR_INTEL:
/*
* There is a known erratum on Pentium III and Core Solo
* and Core Duo CPUs.
* " Page with PAT set to WC while associated MTRR is UC
* may consolidate to UC "
* Because of this erratum, it is better to stick with
* setting WC in MTRR rather than using PAT on these CPUs.
*
* Enable PAT WC only on P4, Core 2 or later CPUs.
*/
if (c->x86 > 0x6 || (c->x86 == 6 && c->x86_model >= 15))
return;
pat_disable("PAT WC disabled due to known CPU erratum.");
return;
case X86_VENDOR_AMD:
case X86_VENDOR_CENTAUR:
case X86_VENDOR_TRANSMETA:
return;
}
pat_disable("PAT disabled. Not yet verified on this CPU type.");
}
#endif
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