misc: add top level makefile

Add a top level makefile to make common tasks easier. Supported targets:

  make           - build modules
  make install   - install modules (honors DESTDIR)
  make clean     - clean up
  make tarballs  - create source tarballs from current HEAD

Note: "make tarballs" uses "git archive" so that it only works in a local
copy of the git repository, not in a directory created by unpacking
a tarball.

Add *.tar to .gitignore to hide tarballs created by "make tarballs".

.gitignore

@@ -3,6 +3,7 @@
 *.ko
 *.ko.cmd
 *.mod.c
+*.tar
 .tmp_versions
 .cache.mk
 Module.symvers

Makefile

@@ -0,0 +1,45 @@
+MODULES = vmmon vmnet
+SUBDIRS = $(MODULES:%=%-only)
+TARBALLS = $(MODULES:%=%.tar)
+MODFILES = $(foreach mod,$(MODULES),$(mod)-only/$(mod).ko)
+VM_UNAME = $(shell uname -r)
+MODDIR = /lib/modules/$(VM_UNAME)/misc
+
+MODINFO = /sbin/modinfo
+DEPMOD = /sbin/depmod
+
+%.tar: FORCE gitcleancheck
+	git archive -o $@ --format=tar HEAD $(@:.tar=-only)
+
+.PHONY: FORCE subdirs $(SUBDIRS) clean tarballs
+
+subdirs: $(SUBDIRS)
+
+FORCE:
+
+$(SUBDIRS):
+	$(MAKE) -C $@ $(MAKECMDGOALS)
+
+gitcheck:
+	@git status >/dev/null 2>&1 \
+	     || ( echo "This only works in a git repository."; exit 1 )
+
+gitcleancheck: gitcheck
+	@git diff --exit-code HEAD >/dev/null 2>&1 \
+	     || echo "Warning: tarballs will reflect current HEAD (no uncommited changes)"
+
+install: $(MODFILES)
+	@for f in $(MODFILES); do \
+	    mver=$$($(MODINFO) -F vermagic $$f);\
+	    mver=$${mver%% *};\
+	    test "$${mver}" = "$(VM_UNAME)" \
+	        || ( echo "Version mismatch: module $$f $${mver}, kernel $(VM_UNAME)" ; exit 1 );\
+	done
+	install -D -t $(DESTDIR)$(MODDIR) $(MODFILES)
+	strip --strip-debug $(MODULES:%=$(DESTDIR)$(MODDIR)/%.ko)
+	if test -z "$(DESTDIR)"; then $(DEPMOD) -a $(VM_UNAME); fi
+
+clean: $(SUBDIRS)
+
+tarballs: $(TARBALLS)
+