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Commit aef93c8b authored by Yinghai Lu's avatar Yinghai Lu Committed by Ingo Molnar
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x86: identify_cpu_without_cpuid v2 



Krzysztof found some old cyrix cpu where an mtrr-alike cpu feature was
not detected properly.

this one is based on Krzysztof' patch, and we call ->c_identify() in
early_identify_cpu.

need to call c_identify() for cpus without cpuid even earlier ...

v2: Krzysztof point out need to give cyrix another chance about cpuid
    checking again, after ->c_identify() enables cpuid for it

Signed-off-by: default avatarYinghai Lu <yhlu.kernel@gmail.com>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e38e05a8

arch/x86/kernel/cpu/common.c

+40 −17
Original line number Diff line number Diff line
@@ -485,6 +485,33 @@ static void __cpuinit get_cpu_cap(struct cpuinfo_x86 *c) 
		c->x86_power = cpuid_edx(0x80000007);



}



static void __cpuinit identify_cpu_without_cpuid(struct cpuinfo_x86 *c)

{

#ifdef CONFIG_X86_32

	int i;



	/*

	 * First of all, decide if this is a 486 or higher

	 * It's a 486 if we can modify the AC flag

	 */

	if (flag_is_changeable_p(X86_EFLAGS_AC))

		c->x86 = 4;

	else

		c->x86 = 3;



	for (i = 0; i < X86_VENDOR_NUM; i++)

		if (cpu_devs[i] && cpu_devs[i]->c_identify) {

			c->x86_vendor_id[0] = 0;

			cpu_devs[i]->c_identify(c);

			if (c->x86_vendor_id[0]) {

				get_cpu_vendor(c);

				break;

			}

		}

#endif

}



/*

 * Do minimum CPU detection early.

 * Fields really needed: vendor, cpuid_level, family, model, mask,
@@ -503,13 +530,16 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) 
#endif

	c->x86_cache_alignment = c->x86_clflush_size;



	if (!have_cpuid_p())

		return;



	memset(&c->x86_capability, 0, sizeof c->x86_capability);



	c->extended_cpuid_level = 0;



	if (!have_cpuid_p())

		identify_cpu_without_cpuid(c);



	/* cyrix could have cpuid enabled via c_identify()*/

	if (!have_cpuid())

		return;



	cpu_detect(c);



	get_cpu_vendor(c);
@@ -583,10 +613,14 @@ static void __cpuinit detect_nopl(struct cpuinfo_x86 *c) 


static void __cpuinit generic_identify(struct cpuinfo_x86 *c)

{

	c->extended_cpuid_level = 0;



	if (!have_cpuid_p())

		return;

		identify_cpu_without_cpuid(c);



	c->extended_cpuid_level = 0;

	/* cyrix could have cpuid enabled via c_identify()*/

	if (!have_cpuid())

		return;



	cpu_detect(c);
@@ -639,17 +673,6 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c) 
	c->x86_cache_alignment = c->x86_clflush_size;

	memset(&c->x86_capability, 0, sizeof c->x86_capability);



	if (!have_cpuid_p()) {

		/*

		 * First of all, decide if this is a 486 or higher

		 * It's a 486 if we can modify the AC flag

		 */

		if (flag_is_changeable_p(X86_EFLAGS_AC))

			c->x86 = 4;

		else

			c->x86 = 3;

	}



	generic_identify(c);



	if (this_cpu->c_identify)