Add support for a saving build objects in a separate directory.

Modifications are based on the linux kernel approach and
support two use cases:

  1) Add O= to the make command line
  'make O=/tmp/build all'

  2) Set environement variable BUILD_DIR to point to the desired location
  'export BUILD_DIR=/tmp/build'
  'make'

The second approach can also be used with a MAKEALL script
'export BUILD_DIR=/tmp/build'
'./MAKEALL'

Command line 'O=' setting overrides BUILD_DIR environent variable.

When none of the above methods is used the local build is performed and
the object files are placed in the source directory.

1 files changed, 8 insertions, 6 deletions

diff --git a/post/rules.mk b/post/rules.mk
index 1ad6959..a2f33ad 100644
--- a/post/rules.mk
+++ b/post/rules.mk
@@ -1,5 +1,5 @@
 #
-# (C) Copyright 2002
+# (C) Copyright 2002-2006
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 #
 # See file CREDITS for list of people who contributed to this
@@ -23,20 +23,22 @@
 
 include $(TOPDIR)/config.mk
 
-OBJS	= $(AOBJS) $(COBJS)
+SRCS 	:= $(AOBJS:.o=.S) $(COBJS:.o=.c)
+OBJS	:= $(addprefix $(obj),$(AOBJS) $(COBJS))
+LIB	:= $(obj)$(LIB)
 
 CPPFLAGS += -I$(TOPDIR)
 
 all:	$(LIB)
 
-$(LIB):	.depend $(OBJS)
+$(LIB):	$(obj).depend $(OBJS)
 	$(AR) crv $@ $(OBJS)
 
 #########################################################################
 
-.depend: Makefile $(AOBJS:.o=.S) $(COBJS:.o=.c)
-	$(CC) -M $(CFLAGS) $(AOBJS:.o=.S) $(COBJS:.o=.c) > .depend
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
 
-sinclude .depend
+sinclude $(obj).depend
 
 #########################################################################