x86, setup: compile with -DDISABLE_BRANCH_PROFILING (95a38f34) · Commits · 戴 / test

Impact: code size reduction (possibly critical) The x86 boot and decompression code has no use of the branch profiling constructs, so disable them. This would bloat the setup code by as much as 14K, eating up a fairly large chunk of the 32K area we are guaranteed to have. Signed-off-by:

H. Peter Anvin <hpa@linux.intel.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/boot/Makefile

+2 −1

Original line number	Diff line number	Diff line
		@@ -57,6 +57,7 @@ $(obj)/cpustr.h: $(obj)/mkcpustr FORCE
		# How to compile the 16-bit code. Note we always compile for -march=i386,
		# that way we can complain to the user if the CPU is insufficient.
		KBUILD_CFLAGS := $(LINUXINCLUDE) -g -Os -D_SETUP -D__KERNEL__ \
		-DDISABLE_BRANCH_PROFILING \
		-Wall -Wstrict-prototypes \
		-march=i386 -mregparm=3 \
		-include $(srctree)/$(src)/code16gcc.h \

arch/x86/boot/compressed/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -8,6 +8,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma h

		KBUILD_CFLAGS := -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2
		KBUILD_CFLAGS += -fno-strict-aliasing -fPIC
		KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
		cflags-$(CONFIG_X86_64) := -mcmodel=small
		KBUILD_CFLAGS += $(cflags-y)
		KBUILD_CFLAGS += $(call cc-option,-ffreestanding)

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