Re: [PATCH] arm64: build with baremetal linker target instead of Linux when available

[Laura Abbott]

On 07/13/2018 08:30 AM, Olof Johansson wrote:

Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
in particular. So, probe for whether it's available and use the previous
(linux) targets if it isn't.

For the Fedora toolchains:

Tested-by: Laura Abbott <labb...@redhat.com>

Reported-by: Laura Abbott <labb...@redhat.com>
Cc: Paul Kocialkowski <cont...@paulk.fr>
Signed-off-by: Olof Johansson <o...@lixom.net>
---
  arch/arm64/Makefile    | 9 +++++----
  scripts/Kbuild.include | 4 ++--
  2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index e7101b19d590..efe61a2e4b5e 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -60,15 +60,16 @@ ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
  KBUILD_CPPFLAGS       += -mbig-endian
  CHECKFLAGS    += -D__AARCH64EB__
  AS            += -EB
-# We must use the linux target here, since distributions don't tend to package
-# the ELF linker scripts with binutils, and this results in a build failure.
-LDFLAGS                += -EB -maarch64linuxb
+# Prefer the baremetal ELF build target, but not all toolchains include
+# it so fall back to the standard linux version if needed.
+LDFLAGS                += -EB $(call ld-option, -maarch64elfb, -maarch64linuxb)
  UTS_MACHINE   := aarch64_be
  else
  KBUILD_CPPFLAGS       += -mlittle-endian
  CHECKFLAGS    += -D__AARCH64EL__
  AS            += -EL
-LDFLAGS                += -EL -maarch64linux # See comment above
+# Same as above, prefer ELF but fall back to linux target if needed.
+LDFLAGS                += -EL $(call ld-option, -maarch64elf, -maarch64linux)
  UTS_MACHINE   := aarch64
  endif

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include

index c8156d61678c..1e13f502b42f 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -163,8 +163,8 @@ cc-ldoption = $(call try-run,\
        $(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o 
"$$TMP",$(1),$(2))

# ld-option

-# Usage: LDFLAGS += $(call ld-option, -X)
-ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2))
+# Usage: LDFLAGS += $(call ld-option, -X, -Y)
+ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2),$(3))

# ar-option

  # Usage: KBUILD_ARFLAGS := $(call ar-option,D)