+CROSS_COMPILE ?=
+# bbox: we may have CONFIG_CROSS_COMPILER_PREFIX in .config,
+# and it has not been included yet... thus using an awkward syntax.
+ifeq ($(CROSS_COMPILE),)
+CROSS_COMPILE := $(shell grep ^CONFIG_CROSS_COMPILER_PREFIX .config 2>/dev/null)
+CROSS_COMPILE := $(subst CONFIG_CROSS_COMPILER_PREFIX=,,$(CROSS_COMPILE))
+CROSS_COMPILE := $(subst ",,$(CROSS_COMPILE))
+endif
+
+# SUBARCH tells the usermode build what the underlying arch is. That is set
+# first, and if a usermode build is happening, the "ARCH=um" on the command
+# line overrides the setting of ARCH below. If a native build is happening,
+# then ARCH is assigned, getting whatever value it gets normally, and
+# SUBARCH is subsequently ignored.
+
+ifneq ($(CROSS_COMPILE),)
+SUBARCH := $(shell echo $(CROSS_COMPILE) | cut -d- -f1)
+else
+SUBARCH := $(shell uname -m)
+endif
+SUBARCH := $(shell echo $(SUBARCH) | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
+ -e s/arm.*/arm/ -e s/sa110/arm/ \
+ -e s/s390x/s390/ -e s/parisc64/parisc/ \
+ -e s/ppc.*/powerpc/ -e s/mips.*/mips/ )
+
+ARCH ?= $(SUBARCH)