x86/build: Turn off -fcf-protection for realmode targets

The new Ubuntu GCC packages turn on -fcf-protection globally,
which causes a build failure in the x86 realmode code:

  cc1: error: ‘-fcf-protection’ is not compatible with this target

Turn it off explicitly on compilers that understand this option.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210323124846.1584944-1-arnd@kernel.org

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 2d6d5a28c3bf791b586d50b8bcb18039c0b62ffc..9a85eae37b17357e8d1b9ee5058b44e6bad2c09d 100644 (file)
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -27,7 +27,7 @@ endif
 REALMODE_CFLAGS        := -m16 -g -Os -DDISABLE_BRANCH_PROFILING \
                   -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
                   -fno-strict-aliasing -fomit-frame-pointer -fno-pic \
-                  -mno-mmx -mno-sse
+                  -mno-mmx -mno-sse $(call cc-option,-fcf-protection=none)
 
 REALMODE_CFLAGS += -ffreestanding
 REALMODE_CFLAGS += -fno-stack-protector