Update Makefile

Makefile

@@ -21,6 +21,16 @@ endif
 
 VERSION = $(shell git describe --tags --always)
 
+# CROSS_COMPILE can be set on the command line
+# make CROSS_COMPILE=arm-linux-gnueabi-
+# Default value for CROSS_COMPILE is not to prefix executables
+
+CROSS_COMPILE ?=
+
+CC		= $(CROSS_COMPILE)gcc
+CXX 		= $(CROSS_COMPILE)g++
+AR		= $(CROSS_COMPILE)ar
+
 debug = 0
 
 PREFIX = /usr/local
@@ -58,7 +68,7 @@ libgraftcp.a: graftcp.o util.o string-set.o conf.o
 	$(CC) $(CFLAGS) -c -o $@ $<
 
 $(GRAFTCP_LOCAL_BIN)::
-	$(MAKE) -C local VERSION=$(VERSION)
+	$(MAKE) -C local VERSION=$(VERSION) CC=$(CC) CXX=$(CXX) AR=$(AR)
 
 install:: graftcp $(GRAFTCP_LOCAL_BIN)
 	$(INSTALL) $< $(DESTDIR)$(BINDIR)/$<

local/Makefile

@@ -2,6 +2,14 @@ ifneq ($(shell echo $(VERSION) | head -c 1), v)
 	VERSION=v0.4
 endif
 
+ifneq (,$(findstring arm,$(CC)))
+	GO_BUILD_PREFIX_FLAGS :=
+	CGO_FLAGS :=
+else
+	GO_BUILD_PREFIX_FLAGS := GOOS=linux GOARCH=arm
+	CGO_FLAGS := CGO_ENABLED=1 CC=$(CC) CXX=$(CXX) AR=$(AR)
+endif
+
 PREFIX = /usr/local
 BINDIR = $(PREFIX)/bin
 
@@ -12,10 +20,10 @@ TARGET = graftcp-local mgraftcp
 all:: $(TARGET)
 
 graftcp-local: $(wildcard *.go cmd/graftcp-local/*.go)
-	go build -ldflags "-s -w -X main.version=${VERSION}" ./cmd/graftcp-local
+	${GO_BUILD_PREFIX_FLAGS} go build -ldflags "-s -w -X main.version=${VERSION}" ./cmd/graftcp-local
 
 mgraftcp: $(wildcard *.go cmd/mgraftcp/*.go) ../libgraftcp.a
-	go build -ldflags "-s -w -X main.version=${VERSION}" ./cmd/mgraftcp
+	${GO_BUILD_PREFIX_FLAGS} ${CGO_FLAGS} go build -ldflags "-s -w -X main.version=${VERSION}" ./cmd/mgraftcp
 
 ../libgraftcp.a:
 	$(MAKE) -C .. libgraftcp.a