-# checker-shell
-# Usage: option = $(call checker-shell, $(CC)...-o $$OUT, option-ok, otherwise)
-# Exit code chooses option. $$OUT is safe location for needless output.
-define checker-shell
- $(shell set -e; \
- DIR=$(KBUILD_EXTMOD); \
- cd $${DIR:-$(objtree)}; \
- OUT=$$PWD/.$$$$.null; \
- \
- ln -s /dev/null $$OUT; \
- if $(1) >/dev/null 2>&1; \
- then echo "$(2)"; \
- else echo "$(3)"; \
- fi; \
- rm -f $$OUT)
-endef
+# cc-cross-prefix
+# Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-)
+# Return first prefix where a prefix$(CC) is found in PATH.
+# If no $(CC) found in PATH with listed prefixes return nothing
+cc-cross-prefix = \
+ $(word 1, $(foreach c,$(1), \
+ $(shell set -e; \
+ if (which $(strip $(c))$(CC)) > /dev/null 2>&1 ; then \
+ echo $(c); \
+ fi)))
+
+# output directory for tests below
+TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/)
+
+# try-run
+# Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise)
+# Exit code chooses option. "$$TMP" is can be used as temporary file and
+# is automatically cleaned up.
+try-run = $(shell set -e; \
+ TMP="$(TMPOUT).$$$$.tmp"; \
+ if ($(1)) >/dev/null 2>&1; \
+ then echo "$(2)"; \
+ else echo "$(3)"; \
+ fi; \
+ rm -f "$$TMP")