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Commit e0022981 authored by Suresh Siddha's avatar Suresh Siddha Committed by H. Peter Anvin
Browse files

x86, fpu: make eagerfpu= boot param tri-state 



Add the "eagerfpu=auto" (that selects the default scheme in
enabling eagerfpu) which can override compiled-in boot parameters
like "eagerfpu=on/off" (that force enable/disable eagerfpu).

Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-5-git-send-email-suresh.b.siddha@intel.com


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 212b0212

Documentation/kernel-parameters.txt

+3 −1
Original line number Diff line number Diff line
@@ -1834,8 +1834,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			enabling legacy floating-point and sse state.



	eagerfpu=	[X86]

			on	enable eager fpu restore (default for xsaveopt)

			on	enable eager fpu restore

			off	disable eager fpu restore

			auto	selects the default scheme, which automatically

				enables eagerfpu restore for xsaveopt.



	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or

			wfi(ARM) instruction doesn't work correctly and not to

arch/x86/kernel/xsave.c

+12 −5
Original line number Diff line number Diff line
@@ -508,13 +508,15 @@ static void __init setup_init_fpu_buf(void) 
	xsave_state(init_xstate_buf, -1);

}



static int disable_eagerfpu;

static enum { AUTO, ENABLE, DISABLE } eagerfpu = AUTO;

static int __init eager_fpu_setup(char *s)

{

	if (!strcmp(s, "on"))

		setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);

		eagerfpu = ENABLE;

	else if (!strcmp(s, "off"))

		disable_eagerfpu = 1;

		eagerfpu = DISABLE;

	else if (!strcmp(s, "auto"))

		eagerfpu = AUTO;

	return 1;

}

__setup("eagerfpu=", eager_fpu_setup);
@@ -557,8 +559,9 @@ static void __init xstate_enable_boot_cpu(void) 
	prepare_fx_sw_frame();

	setup_init_fpu_buf();



	if (cpu_has_xsaveopt && !disable_eagerfpu)

		setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);

	/* Auto enable eagerfpu for xsaveopt */

	if (cpu_has_xsaveopt && eagerfpu != DISABLE)

		eagerfpu = ENABLE;



	pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x\n",

		pcntxt_mask, xstate_size);
@@ -598,6 +601,10 @@ void __cpuinit eager_fpu_init(void) 


	clear_used_math();

	current_thread_info()->status = 0;



	if (eagerfpu == ENABLE)

		setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);



	if (!cpu_has_eager_fpu) {

		stts();

		return;