externalized os.mk

Makefile

@@ -1,14 +1,16 @@
 
+include build/os.mk
+
 all: buildit
 
 buildit:
-	cd build && make all
+	cd build && $(MAKE) all
 
 run: buildit
-	cd build && make run
+	cd build && $(MAKE) run
 
 altrun: buildit
-	cd build && make alt && make altrun
+	cd build && $(MAKE) alt && $(MAKE) altrun
 
 clean:
-	cd build && make clean
+	cd build && $(MAKE) clean

build/Makefile

@@ -1,5 +1,7 @@
 # Build the kernel, the utilities, the filesystem and run SimH
 
+include os.mk
+
 # tools
 AS=../tools/as7
 ASARGS=--format=ptr
@@ -9,38 +11,6 @@ FSCK=../tools/fsck7
 CCARGS=-Wno-multichar
 PDP7=pdp7
 
-# detect OS
-UNAME= $(shell uname)
-ifeq ($(UNAME), Linux)
-	UNAME= LINUX
-else 
-ifeq ($(UNAME), Darwin)
-	UNAME= DARWIN
-else 
-ifeq ($(UNAME), FreeBSD)
-	UNAME= FREEBSD
-endif
-endif
-endif
-
-# choose C compiler
-ifeq ($(UNAME), LINUX)
-# Linux
-	CC=gcc
-else
-ifeq ($(UNAME), FREEBSD)
-# FreeBSD
-	CC=cc
-else
-ifeq ($(UNAME), DARWIN)
-# Mac OS X
-	CC=cc 
-else:
-$(error "Unknown OS: " $(UNAME))
-endif
-endif
-endif
-
 # source dirs
 SYSSRC=../src/sys
 CMDSRC=../src/cmd
@@ -53,7 +23,6 @@ BINDIR=bin
 TESTDIR=tests
 BINARIES=../binaries/
 
-
 all: cmd others a.out boot.rim image.fs
 
 # Make alternative everything: no dd but . and ..

build/os.mk

@@ -0,0 +1,36 @@
+
+# detect OS
+UNAME=$(shell uname)
+ifeq ($(UNAME), Linux)
+	UNAME=LINUX
+	MAKE=make
+else 
+ifeq ($(UNAME), Darwin)
+	UNAME=DARWIN
+	MAKE=make
+else 
+ifeq ($(UNAME), FreeBSD)
+	UNAME=FREEBSD
+	MAKE=gmake
+endif
+endif
+endif
+
+# choose C compiler
+ifeq ($(UNAME), LINUX)
+# Linux
+	CC=gcc
+else
+ifeq ($(UNAME), FREEBSD)
+# FreeBSD
+	CC=cc
+else
+ifeq ($(UNAME), DARWIN)
+# Mac OS X
+	CC=cc 
+else
+	$(error "Unknown OS: " $(UNAME))
+endif
+endif
+endif
+