linux-kernel - [PATCH] kbuild: drop support for cc-ldoption

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Message-Id: <20190423212741.12219-1-ndesaulniers@google.com>
Date:   Tue, 23 Apr 2019 14:27:41 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     yamada.masahiro@...ionext.com, michal.lkml@...kovi.net,
        corbet@....net
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com, linux-kbuild@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] kbuild: drop support for cc-ldoption

If you want to see if your linker supports a certain flag, then ask the
linker directly with ld-option (not the compiler with cc-ldoption).
Checking for linker flag support is an antipattern that complicates the
usage of various linkers other than bfd via -fuse-ld={bfd|gold|lld}.

Cc: clang-built-linux@...glegroups.com
Suggested-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
---
This should probably wait until all of the call sites have been cleaned
up. Masahiro sent them for arm and arm64, while I sent cleanups for all
the rest.


 Documentation/kbuild/makefiles.txt | 14 --------------
 scripts/Kbuild.include             |  5 -----
 2 files changed, 19 deletions(-)

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 03c065855eaf..d65ad5746f94 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -437,20 +437,6 @@ more details, with real examples.
 	The second argument is optional, and if supplied will be used
 	if first argument is not supported.
 
-    cc-ldoption
-	cc-ldoption is used to check if $(CC) when used to link object files
-	supports the given option.  An optional second option may be
-	specified if first option are not supported.
-
-	Example:
-		#arch/x86/kernel/Makefile
-		vsyscall-flags += $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
-
-	In the above example, vsyscall-flags will be assigned the option
-	-Wl$(comma)--hash-style=sysv if it is supported by $(CC).
-	The second argument is optional, and if supplied will be used
-	if first argument is not supported.
-
     as-instr
 	as-instr checks if the assembler reports a specific instruction
 	and then outputs either option1 or option2
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 7484b9d8272f..fbfb37d1bcc8 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -138,11 +138,6 @@ cc-disable-warning = $(call try-run,\
 # Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
 cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
 
-# cc-ldoption
-# Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)
-cc-ldoption = $(call try-run,\
-	$(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
-
 # ld-option
 # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
 ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
-- 
2.21.0.593.g511ec345e18-goog