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x86/cpu: Provide a config option to disable static_cpu_has 

This brings .text savings of about ~1.6K when building a tinyconfig. It
is off by default so nothing changes for the default.

Kconfig help text from Josh.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Link: http://lkml.kernel.org/r/1449481182-27541-5-git-send-email-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
hifive-unleashed-5.1
Borislav Petkov 2015-12-07 10:39:42 +01:00 committed by Thomas Gleixner
parent 362f924b64
commit 6e1315fe82
2 changed files with 12 additions and 1 deletions
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11
arch/x86/Kconfig
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@ -349,6 +349,17 @@ config X86_FEATURE_NAMES
If in doubt, say Y.
config X86_FAST_FEATURE_TESTS
bool "Fast CPU feature tests" if EMBEDDED
default y
---help---
Some fast-paths in the kernel depend on the capabilities of the CPU.
Say Y here for the kernel to patch in the appropriate code at runtime
based on the capabilities of the CPU. The infrastructure for patching
code at runtime takes up some additional space; space-constrained
embedded systems may wish to say N here to produce smaller, slightly
slower code.
config X86_X2APIC
bool "Support x2apic"
depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)

2
arch/x86/include/asm/cpufeature.h
View File

@ -409,7 +409,7 @@ extern const char * const x86_bug_flags[NBUGINTS*32];
* fast paths and boot_cpu_has() otherwise!
*/
#if __GNUC__ >= 4
#if __GNUC__ >= 4 && defined(CONFIG_X86_FAST_FEATURE_TESTS)
extern void warn_pre_alternatives(void);
extern bool __static_cpu_has_safe(u16 bit);