Commit 691ef3e7 authored by Sam Ravnborg's avatar Sam Ravnborg

kbuild: introduce ld-option

ld-option is used to check if $(LD) supports a specific option.

Based on patch from Andi Kleen.

Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: 's avatarSam Ravnborg <sam@ravnborg.org>
First use is to check if option -X is supported (upcoming patch).
Theis is ne
parent f86fd306
......@@ -18,6 +18,7 @@ This document describes the Linux kernel Makefiles.
--- 3.9 Dependency tracking
--- 3.10 Special Rules
--- 3.11 $(CC) support functions
--- 3.12 $(LD) support functions
=== 4 Host Program support
--- 4.1 Simple Host Program
......@@ -570,6 +571,19 @@ more details, with real examples.
endif
endif
--- 3.12 $(LD) support functions
ld-option
ld-option is used to check if $(LD) supports the supplied option.
ld-option takes two options as arguments.
The second argument is an optional option that can be used if the
first option is not supported by $(LD).
Example:
#Makefile
LDFLAGS_vmlinux += $(call really-ld-option, -X)
=== 4 Host Program support
Kbuild supports building executables on the host for use during the
......
......@@ -83,11 +83,12 @@ TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
# is automatically cleaned up.
try-run = $(shell set -e; \
TMP="$(TMPOUT).$$$$.tmp"; \
TMPO="$(TMPOUT).$$$$.o"; \
if ($(1)) >/dev/null 2>&1; \
then echo "$(2)"; \
else echo "$(3)"; \
fi; \
rm -f "$$TMP")
rm -f "$$TMP" "$$TMPO")
# as-option
# Usage: cflags-y += $(call as-option,-Wa$(comma)-isa=foo,)
......@@ -135,6 +136,11 @@ cc-ifversion = $(shell [ $(call cc-version, $(CC)) $(1) $(2) ] && echo $(3))
cc-ldoption = $(call try-run,\
$(CC) $(1) -nostdlib -xc /dev/null -o "$$TMP",$(1),$(2))
# ld-option
# Usage: LDFLAGS += $(call ld-option, -X)
ld-option = $(call try-run,\
$(CC) /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))
######
###
......
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