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x86, compress: Force i386 instructions for the decompressor

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Recently, some distros have started shipping versions of gcc which
default to -march=i686.  This breaks building kernels for pre-i686
machines, even if they have been selected in Kconfig, due to the
generation of CMOV instructions.

There isn't enough benefit to try to preserve the generation of these
instructions even when selected, so simply force -march=i386 for the
decompressor when building a 32-bit kernel.

Reported-and-tested-by: Chris Rankin <rankincj@yahoo.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <219280.97558.qm@web52907.mail.re2.yahoo.com>
This commit is contained in:
H. Peter Anvin 2009-12-25 15:40:38 -08:00
parent 8bee738bb1
commit 17a2a9b57a
1 changed files with 1 additions and 0 deletions
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arch/x86/boot/compressed/Makefile
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@ -9,6 +9,7 @@ targets := vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinu
KBUILD_CFLAGS := -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2
KBUILD_CFLAGS += -fno-strict-aliasing -fPIC
KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
cflags-$(CONFIG_X86_32) := -march=i386
cflags-$(CONFIG_X86_64) := -mcmodel=small
KBUILD_CFLAGS += $(cflags-y)
KBUILD_CFLAGS += $(call cc-option,-ffreestanding)