[PATCH] uml: start cross-build support : mk_user_constants

Beginning of cross-build fixes.  Instead of expecting that mk_user_constants
(compiled and executed on the build box) will see the sizeof, etc.  for target
box, we do what every architecture already does for asm-offsets.  Namely, have
user-offsets.c compiled *for* *target* into user-offsets.s and sed it into the
header with relevant constants.  We don't need to reinvent any wheels - all
tools are already there.

This patch deals with mk_user_constants.  It doesn't assume any relationship
between target and build environment anymore - we pick all defines we need
from user-offsets.h.  Later patches will deal with the rest of mk_...  helpers
in the same way.

Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 1d13664..e3465da 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -166,6 +166,14 @@
 $(ARCH_DIR)/include/uml-config.h : include/linux/autoconf.h
 	$(call filechk,umlconfig)
 
+$(ARCH_DIR)/user-offsets.s: $(ARCH_DIR)/sys-$(SUBARCH)/user-offsets.c
+	$(CC) $(USER_CFLAGS) -S -o $@ $<
+
+$(ARCH_DIR)/user-offsets.h: $(ARCH_DIR)/user-offsets.s
+	$(call filechk,gen-asm-offsets)
+
+CLEAN_FILES += $(ARCH_DIR)/user-offsets.s  $(ARCH_DIR)/user-offsets.h
+
 $(ARCH_DIR)/include/task.h: $(ARCH_DIR)/util/mk_task
 	$(call filechk,gen_header)