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

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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: Suresh 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: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Suresh Siddha 2012-09-10 10:32:32 -07:00 committed by H. Peter Anvin
parent 212b02125f
commit e00229819f
2 changed files with 15 additions and 6 deletions
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4
Documentation/kernel-parameters.txt
View file

@ -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

17
arch/x86/kernel/xsave.c
View file

@ -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;