queue-4.9/kbuild-simplify-ld-option-implementation.patch

   1 From e9376686d5827beee5a36c47753bf438952a6621 Mon Sep 17 00:00:00 2001
   2 From: Masahiro Yamada <yamada.masahiro@socionext.com>
   3 Date: Fri, 23 Feb 2018 13:56:53 +0900
   4 Subject: kbuild: simplify ld-option implementation
   5
   6 From: Masahiro Yamada <yamada.masahiro@socionext.com>
   7
   8 commit 0294e6f4a0006856e1f36b8cd8fa088d9e499e98 upstream.
   9
  10 Currently, linker options are tested by the coordination of $(CC) and
  11 $(LD) because $(LD) needs some object to link.
  12
  13 As commit 86a9df597cdd ("kbuild: fix linker feature test macros when
  14 cross compiling with Clang") addressed, we need to make sure $(CC)
  15 and $(LD) agree the underlying architecture of the passed object.
  16
  17 This could be a bit complex when we combine tools from different groups.
  18 For example, we can use clang for $(CC), but we still need to rely on
  19 GCC toolchain for $(LD).
  20
  21 So, I was searching for a way of standalone testing of linker options.
  22 A trick I found is to use '-v'; this not only prints the version string,
  23 but also tests if the given option is recognized.
  24
  25 If a given option is supported,
  26
  27   $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419
  28   GNU ld (Linaro_Binutils-2017.11) 2.28.2.20170706
  29   $ echo $?
  30   0
  31
  32 If unsupported,
  33
  34   $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419
  35   GNU ld (crosstool-NG linaro-1.13.1-4.7-2013.04-20130415 - Linaro GCC 2013.04) 2.23.1
  36   aarch64-linux-gnu-ld: unrecognized option '--fix-cortex-a53-843419'
  37   aarch64-linux-gnu-ld: use the --help option for usage information
  38   $ echo $?
  39   1
  40
  41 Gold works likewise.
  42
  43   $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-843419
  44   GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14
  45   masahiro@pug:~/ref/linux$ echo $?
  46   0
  47   $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-999999
  48   GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14
  49   aarch64-linux-gnu-ld.gold: --fix-cortex-a53-999999: unknown option
  50   aarch64-linux-gnu-ld.gold: use the --help option for usage information
  51   $ echo $?
  52   1
  53
  54 LLD too.
  55
  56   $ ld.lld -v --gc-sections
  57   LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers)
  58   $ echo $?
  59   0
  60   $ ld.lld -v --fix-cortex-a53-843419
  61   LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers)
  62   $ echo $?
  63   0
  64   $ ld.lld -v --fix-cortex-a53-999999
  65   ld.lld: error: unknown argument: --fix-cortex-a53-999999
  66   LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers)
  67   $ echo $?
  68   1
  69
  70 Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
  71 Tested-by: Nick Desaulniers <ndesaulniers@google.com>
  72 [nc: try-run-cached was added later, just use try-run, which is the
  73      current mainline state]
  74 Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
  75 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  76 ---
  77  scripts/Kbuild.include |    4 +---
  78  1 file changed, 1 insertion(+), 3 deletions(-)
  79
  80 --- a/scripts/Kbuild.include
  81 +++ b/scripts/Kbuild.include
  82 @@ -166,9 +166,7 @@ cc-ldoption = $(call try-run,\
  83
  84  # ld-option
  85  # Usage: LDFLAGS += $(call ld-option, -X)
  86 -ld-option = $(call try-run,\
  87 -       $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -x c /dev/null -c -o "$$TMPO"; \
  88 -       $(LD) $(LDFLAGS) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))
  89 +ld-option = $(call try-run, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2))
  90
  91  # ar-option
  92  # Usage: KBUILD_ARFLAGS := $(call ar-option,D)