From: Borislav Petkov <bp@xxxxxxx> commit 6e1315fe82308cd29e7550eab967262e8bbc71a3 upstream 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@xxxxxxx> Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1449481182-27541-5-git-send-email-bp@xxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Srivatsa S. Bhat <srivatsa@xxxxxxxxxxxxx> Reviewed-by: Matt Helsley (VMware) <matt.helsley@xxxxxxxxx> Reviewed-by: Alexey Makhalov <amakhalov@xxxxxxxxxx> Reviewed-by: Bo Gan <ganb@xxxxxxxxxx> --- arch/x86/Kconfig | 11 +++++++++++ arch/x86/include/asm/cpufeature.h | 2 +- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index eab1ef2..d9afe6d 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -346,6 +346,17 @@ 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) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 54c7a0b..67f917b 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -422,7 +422,7 @@ 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);
