kbuild: introduce cc-cross-prefix
cc-cross-prefix is useful for the architecture that like
to provide a default CROSS_COMPILE value,
but may have several to select between.
Sample usage:
ifneq ($(SUBARCH),$(ARCH))
ifeq ($(CROSS_COMPILE),)
CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
endif
endif
Actual usage by the different archs will taken care of later.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index f099b81..6166e2d 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -518,6 +518,28 @@
In this example for a specific GCC version the build will error out explaining
to the user why it stops.
+ cc-cross-prefix
+ cc-cross-prefix is used to check if there exist a $(CC) in path with
+ one of the listed prefixes. The first prefix where there exist a
+ prefix$(CC) in the PATH is returned - and if no prefix$(CC) is found
+ then nothing is returned.
+ Additional prefixes are separated by a single space in the
+ call of cc-cross-prefix.
+ This functionality is usefull for architecture Makefile that try
+ to set CROSS_COMPILE to well know values but may have several
+ values to select between.
+ It is recommended only to try to set CROSS_COMPILE is it is a cross
+ build (host arch is different from target arch). And is CROSS_COMPILE
+ is already set then leave it with the old value.
+
+ Example:
+ #arch/m68k/Makefile
+ ifneq ($(SUBARCH),$(ARCH))
+ ifeq ($(CROSS_COMPILE),)
+ CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu-)
+ endif
+ endif
+
=== 4 Host Program support
Kbuild supports building executables on the host for use during the
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index de7bb28..b96ea8d 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -56,6 +56,17 @@
# gcc support functions
# See documentation in Documentation/kbuild/makefiles.txt
+# cc-cross-prefix
+# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
+# Return first prefix where a prefix$(CC) is found in PATH.
+# If no $(CC) found in PATH with listed prefixes return nothing
+cc-cross-prefix = \
+ $(word 1, $(foreach c,$(1), \
+ $(shell set -e; \
+ if (which $(strip $(c))$(CC)) > /dev/null 2>&1 ; then \
+ echo $(c); \
+ fi)))
+
# output directory for tests below
TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
