arm64: kill off the libgcc dependency

The arm64 kernel builds fine without the libgcc. Actually it should not
be used at all in the kernel. The following are the reasons indicated
by Russell King:

  Although libgcc is part of the compiler, libgcc is built with the
  expectation that it will be running in userland - it expects to link
  to a libc.  That's why you can't build libgcc without having the glibc
  headers around.

  [...]

  Meanwhile, having the kernel build the compiler support functions that
  it needs ensures that (a) we know what compiler support functions are
  being used, (b) we know the implementation of those support functions
  are sane for use in the kernel, (c) we can build them with appropriate
  compiler flags for best performance, and (d) we remove an unnecessary
  dependency on the build toolchain.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 1c43cec971b5cd7196b367d1917baa25a10078bd..a20c28348be438086a05af3b812ebce7ecaa4ed8 100644 (file)
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -15,8 +15,6 @@ CPPFLAGS_vmlinux.lds = -DTEXT_OFFSET=$(TEXT_OFFSET)
 OBJCOPYFLAGS   :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
 GZFLAGS                :=-9
 
-LIBGCC                 := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
-
 KBUILD_DEFCONFIG := defconfig
 
 KBUILD_CFLAGS  += -mgeneral-regs-only
@@ -50,7 +48,6 @@ core-$(CONFIG_KVM) += arch/arm64/kvm/
 core-$(CONFIG_XEN) += arch/arm64/xen/
 core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
 libs-y         := arch/arm64/lib/ $(libs-y)
-libs-y         += $(LIBGCC)
 libs-$(CONFIG_EFI_STUB) += drivers/firmware/efi/libstub/
 
 # Default target when executing plain make