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addon_cpuid_features.c

/*
 *    Routines to indentify additional cpu features that are scattered in
 *    cpuid space.
 */

#include <linux/cpu.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, &regs[CR_EAX], &regs[CR_EBX],
                  &regs[CR_ECX], &regs[CR_EDX]);

            if (regs[cb->reg] & (1 << cb->bit))
                  set_bit(cb->feature, c->x86_capability);
      }
}

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