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>

1 files changed, 11 insertions, 0 deletions

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index de7bb284c611..b96ea8d6a5ed 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -56,6 +56,17 @@ endef
 # 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))/)