Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 212b0212 authored by Suresh Siddha's avatar Suresh Siddha Committed by H. Peter Anvin
Browse files

x86, fpu: enable eagerfpu by default for xsaveopt 



xsaveopt/xrstor support optimized state save/restore by tracking the
INIT state and MODIFIED state during context-switch.

Enable eagerfpu by default for processors supporting xsaveopt.
Can be disabled by passing "eagerfpu=off" boot parameter.

Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-3-git-send-email-suresh.b.siddha@intel.com


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 5d2bd700

Documentation/kernel-parameters.txt

+1 −1
Original line number Diff line number Diff line
@@ -1834,7 +1834,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			enabling legacy floating-point and sse state.



	eagerfpu=	[X86]

			on	enable eager fpu restore

			on	enable eager fpu restore (default for xsaveopt)

			off	disable eager fpu restore



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

arch/x86/include/asm/cpufeature.h

+1 −0
Original line number Diff line number Diff line
@@ -300,6 +300,7 @@ extern const char * const x86_power_flags[32]; 
#define cpu_has_xmm4_2		boot_cpu_has(X86_FEATURE_XMM4_2)

#define cpu_has_x2apic		boot_cpu_has(X86_FEATURE_X2APIC)

#define cpu_has_xsave		boot_cpu_has(X86_FEATURE_XSAVE)

#define cpu_has_xsaveopt	boot_cpu_has(X86_FEATURE_XSAVEOPT)

#define cpu_has_osxsave		boot_cpu_has(X86_FEATURE_OSXSAVE)

#define cpu_has_hypervisor	boot_cpu_has(X86_FEATURE_HYPERVISOR)

#define cpu_has_pclmulqdq	boot_cpu_has(X86_FEATURE_PCLMULQDQ)

arch/x86/kernel/xsave.c

+3 −0
Original line number Diff line number Diff line
@@ -557,6 +557,9 @@ 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);



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

		pcntxt_mask, xstate_size);

}