Link and C flags are also specified in dune-accessible files.

For mirage/mirage#969
Instead of pkg-config, one can use the following files to get the
compilation flags:

ocaml-freestanding/libs
ocaml-freestanding/cflags

Makefile

@@ -13,7 +13,7 @@ FREESTANDING_LIBS=build/openlibm/libopenlibm.a \
 		  build/nolibc/libnolibc.a
 endif
 
-all:	$(FREESTANDING_LIBS) ocaml-freestanding.pc
+all:	$(FREESTANDING_LIBS) ocaml-freestanding.pc flags/libs flags/cflags
 
 Makeconf:
 	./configure.sh
@@ -100,6 +100,24 @@ ocaml-freestanding.pc: ocaml-freestanding.pc.in Makeconf
 	    -e 's!@@PKG_CONFIG_EXTRA_LIBS@@!$(PKG_CONFIG_EXTRA_LIBS)!' \
 	    ocaml-freestanding.pc.in > $@
 
+flags/libs: flags/libs.tmp Makeconf
+	sed -e 's!@@PKG_CONFIG_EXTRA_LIBS@@!$(PKG_CONFIG_EXTRA_LIBS)!' \
+	    flags/libs.tmp > flags/libs.tmp2
+	for PKG in $(PKG_CONFIG_DEPS); do \
+		echo " " >> flags/libs.tmp2;\
+		env PKG_CONFIG_PATH=$(shell opam config var prefix)/lib/pkgconfig pkg-config $$PKG --libs >> flags/libs.tmp2;\
+	done
+	echo "("`cat flags/libs.tmp2`")" > flags/libs
+
+flags/cflags: flags/cflags.tmp Makeconf
+	for PKG in $(PKG_CONFIG_DEPS); do \
+		echo " " >> flags/cflags.tmp;\
+		env PKG_CONFIG_PATH=$(shell opam config var prefix)/lib/pkgconfig pkg-config $$PKG --cflags >> flags/cflags.tmp;\
+	done
+	echo "("`cat flags/cflags.tmp`")" > flags/cflags
+
+
+
 install: all
 	./install.sh
 

flags/cflags.tmp.in

@@ -0,0 +1 @@
+-I%{prefix}%/include/ocaml-freestanding

flags/libs.tmp.in

@@ -0,0 +1 @@
+-L%{ocaml-freestanding:lib}% -lasmrun -lnolibc -lopenlibm @@PKG_CONFIG_EXTRA_LIBS@@

install.sh

@@ -54,3 +54,5 @@ touch ${DESTLIB}/META
 # pkg-config
 mkdir -p ${prefix}/lib/pkgconfig
 cp ocaml-freestanding.pc ${prefix}/lib/pkgconfig/ocaml-freestanding.pc
+cp flags/cflags ${DESTLIB}
+cp flags/libs ${DESTLIB}

opam

@@ -16,6 +16,10 @@ depends: [
   ("solo5-bindings-hvt" | "solo5-bindings-virtio" | "solo5-bindings-muen" | "solo5-bindings-genode")
   "ocaml" {>= "4.04.2" & < "4.08.0"}
 ]
+substs: [
+  "flags/cflags.tmp"
+  "flags/libs.tmp"
+]
 conflicts: [
   "sexplib" {= "v0.9.0"}
   "solo5-kernel-ukvm"