Provide standard Makefile rules for clients of liblitmus

We avoid doing the same thing over and over in all repositories using
liblitmus if we just pull in common rules & configurations from
liblitmus. This gives us the ability to cross-compile for free.

2 files changed, 46 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index 54f4b57..0738648 100644
--- a/Makefile
+++ b/Makefile
@@ -41,8 +41,11 @@ unistd-x86_64    = unistd.h unistd_64.h
 # default: unistd.h
 unistd-${ARCH}  ?= unistd.h
 
+# by default we use the local version
+LIBLITMUS ?= .
+
 # where to find header files
-headers = -Iinclude -Iarch/${include-${ARCH}}/include
+headers = -I${LIBLITMUS}/include -I${LIBLITMUS}/arch/${include-${ARCH}}/include
 
 # combine options
 CPPFLAGS = ${flags-api} ${flags-${ARCH}} -DARCH=${ARCH} ${headers}
@@ -50,7 +53,7 @@ CFLAGS   = ${flags-debug}
 LDFLAGS  = ${flags-${ARCH}}
 
 # how to link against liblitmus
-liblitmus-flags = -L. -llitmus
+liblitmus-flags = -L${LIBLITMUS} -llitmus
 
 # Force gcc instead of cc, but let the user specify a more specific version if
 # desired.
@@ -72,7 +75,24 @@ rt-apps = cycles base_task rt_launch rtspin release_ts measure_syscall \
 
 .PHONY: all lib clean dump-config
 
-all: ${all}
+all: ${all} inc/config.makefile
+
+# Write a distilled version of the flags for clients of the library. Ideally,
+# this should depend on liblitmus.a, but that requires LIBLITMUS to be a
+# private override. Private overrides are only supported starting with make
+# 3.82, which is not yet in common use.
+inc/config.makefile: LIBLITMUS = $${LIBLITMUS}
+inc/config.makefile: Makefile
+        @printf "%-15s= %-20s\n" \
+                ARCH ${ARCH} \
+                CFLAGS '${CFLAGS}' \
+                LDFLAGS '${LDFLAGS}' \
+                LDLIBS '${liblitmus-flags}' \
+                CPPFLAGS '${CPPFLAGS}' \
+                CC '${shell which ${CC}}' \
+                LD '${shell which ${LD}}' \
+                AR '${shell which ${AR}}' \
+        > $@
 
 dump-config:
         @echo Build configuration:
@@ -95,6 +115,7 @@ clean:
         rm -f ${rt-apps}
         rm -f *.o *.d *.a test_catalog.inc
         rm -f ${imported-headers}
+        rm -f inc/config.makefile
 
 # ##############################################################################
 # Kernel headers.
diff --git a/inc/depend.makefile b/inc/depend.makefile
new file mode 100644
index 0000000..4d10534
--- /dev/null
+++ b/inc/depend.makefile
@@ -0,0 +1,22 @@
+# Generic dependency resolution. Part of liblitmus so that we don't have to
+#  carry it around in every project using liblitmus.
+
+obj-all = ${sort ${foreach target,${all},${obj-${target}}}}
+
+# rule to generate dependency files
+%.d: %.c
+        @set -e; rm -f $@; \
+                $(CC) -MM $(CPPFLAGS) $< > $@.$$$$; \
+                sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \
+                rm -f $@.$$$$
+
+ifeq ($(MAKECMDGOALS),)
+MAKECMDGOALS += all
+endif
+
+ifneq ($(filter-out clean,$(MAKECMDGOALS)),)
+
+# Pull in dependencies.
+-include ${obj-all:.o=.d}
+
+endif