kbuild: Fix UML build

Not perfectly clean yet, but uses the standard way to descend into subdirs
and gives me working vmlinux and linux targets without spurious rebuilds.

arch/um/Makefile

@@ -51,14 +51,6 @@ LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc
 
 SIZE = (($(CONFIG_NEST_LEVEL) + $(CONFIG_KERNEL_HALF_GIGS)) * 0x20000000)
 
-$(ARCH_DIR)/uml.lds.s : $(ARCH_DIR)/uml.lds.S
-	$(call if_changed_dep,as_s_S)
-
-AFLAGS_uml.lds.o = -U$(SUBARCH) -DSTART=$$(($(TOP_ADDR) - $(SIZE))) \
-	-DELF_ARCH=$(ELF_ARCH) -DELF_FORMAT=\"$(ELF_FORMAT)\" -P -C -Uum
-
-LDFLAGS_vmlinux = -r $(ARCH_DIR)/main.o
-
 SYMLINK_HEADERS = include/asm-um/archparam.h include/asm-um/system.h \
 	include/asm-um/sigcontext.h include/asm-um/processor.h \
 	include/asm-um/ptrace.h include/asm-um/arch-signal.h
@@ -71,11 +63,25 @@ GEN_HEADERS = $(ARCH_DIR)/include/task.h
 $(ARCH_DIR)/vmlinux.lds.S :
 	touch $@
 
-linux: scripts $(ARCH_SYMLINKS) $(SYS_HEADERS) $(GEN_HEADERS) \
-	arch/um/uml.lds.s $(ARCH_DIR)/main.o vmlinux
+prepare: $(ARCH_SYMLINKS) $(GEN_HEADERS)
+
+
+LDFLAGS_vmlinux = -r $(ARCH_DIR)/main.o
+
+vmlinux: $(ARCH_DIR)/main.o 
+
+
+$(ARCH_DIR)/uml.lds.s : $(ARCH_DIR)/uml.lds.S
+	$(call if_changed_dep,as_s_S)
+
+AFLAGS_uml.lds.o = -U$(SUBARCH) -DSTART=$$(($(TOP_ADDR) - $(SIZE))) \
+	-DELF_ARCH=$(ELF_ARCH) -DELF_FORMAT=\"$(ELF_FORMAT)\" -P -C -Uum
+
+linux: arch/um/uml.lds.s vmlinux
 	$(CC) -Wl,-T,arch/um/uml.lds.s -o $@ $(LINK_PROFILE) \
 	$(LINK_WRAPS) -static vmlinux -L/usr/lib -lutil
 
+
 USER_CFLAGS := $(patsubst -I%,,$(CFLAGS))
 USER_CFLAGS := $(patsubst -Derrno=kernel_errno,,$(USER_CFLAGS))
 USER_CFLAGS := $(patsubst -D__KERNEL__,,$(USER_CFLAGS)) -I$(ARCH_INCLUDE)
@@ -125,8 +131,9 @@ arch/um/os:
 $(ARCH_DIR)/include/task.h : $(ARCH_DIR)/util/mk_task
 	$< > $@
 
-$(ARCH_DIR)/util/mk_task : $(ARCH_DIR)/util/mk_task_user.c \
-	$(ARCH_DIR)/util/mk_task_kern.c 
-	$(MAKE) $(MFLAGS) -C $(ARCH_DIR)/util all
+$(ARCH_DIR)/util/mk_task : $(ARCH_DIR)/util FORCE ;
+
+$(ARCH_DIR)/util: FORCE
+	@$(call descend,$@,)
 
 export SUBARCH USER_CFLAGS OS

arch/um/Makefile-i386

@@ -8,27 +8,24 @@ ARCH_CFLAGS = -U__$(SUBARCH)__ -U$(SUBARCH)
 ELF_ARCH = $(SUBARCH)
 ELF_FORMAT = elf32-$(SUBARCH)
 
+SYS_DIR		:= $(ARCH_DIR)/include/sysdep-i386
+SYS_UTIL_DIR	:= $(ARCH_DIR)/sys-i386/util
 
-SYS_HEADERS = $(ARCH_DIR)/include/sysdep-i386/sc.h \
-	$(ARCH_DIR)/include/sysdep-i386/thread.h
+SYS_HEADERS = $(SYS_DIR)/sc.h $(SYS_DIR)/thread.h
 
-$(ARCH_DIR)/include/sysdep-i386/sc.h : $(ARCH_DIR)/sys-i386/util/mk_sc \
-	include/asm
-	$(ARCH_DIR)/sys-i386/util/mk_sc > $@
+prepare: $(SYS_HEADERS)
 
-$(ARCH_DIR)/include/sysdep-i386/thread.h : $(ARCH_DIR)/sys-i386/util/mk_thread\
-	include/asm
-	$(ARCH_DIR)/sys-i386/util/mk_thread > $@
+$(SYS_DIR)/sc.h: $(SYS_UTIL_DIR)/mk_sc
+	$< > $@
 
-$(ARCH_DIR)/sys-i386/util/mk_sc : $(ARCH_DIR)/sys-i386/util/mk_sc.c \
-	include/asm
-	$(MAKE) -C $(ARCH_DIR)/sys-i386/util mk_sc
+$(SYS_DIR)/thread.h: $(SYS_UTIL_DIR)/mk_thread
+	$< > $@
 
-$(ARCH_DIR)/sys-i386/util/mk_thread : \
-	$(ARCH_DIR)/sys-i386/util/mk_thread_user.c \
-	$(ARCH_DIR)/sys-i386/util/mk_thread_kern.c
-	$(MAKE) -C $(ARCH_DIR)/sys-i386/util mk_thread
+$(SYS_UTIL_DIR)/mk_sc $(SYS_UTIL_DIR)/mk_thread: $(SYS_UTIL_DIR) FORCE ; 
+
+$(SYS_UTIL_DIR): include/asm FORCE
+	@$(call descend,$@,)
 
 sysclean :
 	rm -f $(SYS_HEADERS)
-	make -C $(ARCH_DIR)/sys-i386/util clean
+	@$(call descend,$(SYS_DIR),clean)

arch/um/sys-i386/util/Makefile

-host-progs = mk_sc
+EXTRA_TARGETS	:= mk_sc mk_thread mk_thread_kern.o
 
-mk_sc-objs = mk_sc.o
+host-progs	:= mk_sc
+
+mk_sc-objs	:= mk_sc.o
 
 include $(TOPDIR)/Rules.make
 
-mk_thread : mk_thread_kern.o mk_thread_user.o
-	$(CC) $(CFLAGS) -o $@ mk_thread_user.o mk_thread_kern.o
+$(obj)/mk_thread : $(obj)/mk_thread_kern.o $(obj)/mk_thread_user.o
+	$(CC) $(CFLAGS) -o $@ $^
 
-mk_thread_user.o : mk_thread_user.c
+$(obj)/mk_thread_user.o : $(src)/mk_thread_user.c
 	$(CC) $(USER_CFLAGS) -c -o $@ $<
 
 clean :
-	$(RM) $(host-progs) mk_thread
+	$(RM) -f $(EXTRA_TARGETS)
 
 archmrproper : clean

arch/um/util/Makefile

-include $(TOPDIR)/Rules.make
+EXTRA_TARGETS := mk_task mk_task_kern.o
 
-all : mk_task
+include $(TOPDIR)/Rules.make
 
-mk_task : mk_task_user.o mk_task_kern.o
-	$(CC) -o mk_task mk_task_user.o mk_task_kern.o
+$(obj)/mk_task: $(obj)/mk_task_user.o $(obj)/mk_task_kern.o
+	$(CC) -o $@ $^
 
-mk_task_user.o : mk_task_user.c
-	$(CC) -c $< 
+$(obj)/mk_task_user.o: $(src)/mk_task_user.c
+	$(CC) -o $@ -c $< 
 
-clean :
-	$(RM) mk_task *.o *~
+clean:
+	$(RM) $(EXTRA_TARGETS)
 
-archmrproper : clean
+archmrproper: