[PATCH 3/9] sandbox: source/invoke um Makefiles provided by host architecture

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

It can make sense to use an existing arch's implementation for low-level
things like setjmp/longjmp. Copy the Linux scheme that enables this.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 Makefile                |  2 ++
 arch/sandbox/Makefile   |  9 +++++++++
 scripts/subarch.include | 11 +++++++++++
 3 files changed, 22 insertions(+)
 create mode 100644 scripts/subarch.include

diff --git a/Makefile b/Makefile
index aa66d0cf3b38..bc75c6335177 100644
--- a/Makefile
+++ b/Makefile
@@ -321,6 +321,8 @@ KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(S
 BUILDSYSTEM_VERSION =
 export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION BUILDSYSTEM_VERSION
 
+include $(srctree)/scripts/subarch.include
+
 # Cross compiling and selecting different set of gcc/bin-utils
 # ---------------------------------------------------------------------------
 #
diff --git a/arch/sandbox/Makefile b/arch/sandbox/Makefile
index 8f6425760619..157e856c59b1 100644
--- a/arch/sandbox/Makefile
+++ b/arch/sandbox/Makefile
@@ -19,6 +19,14 @@ board-y := arch/sandbox/board
 BOARD	:= $(board-y)/
 lds-y   := $(BOARD)/barebox.lds
 
+HEADER_ARCH 	:= $(SUBARCH)
+HOST_DIR := arch/$(HEADER_ARCH)
+
+-include $(srctree)/$(HOST_DIR)/Makefile.um
+
+common-y += $(HOST_DIR)/um/
+
+KBUILD_CPPFLAGS += -I$(srctree)/$(HOST_DIR)/include
 
 TEXT_BASE = $(CONFIG_TEXT_BASE)
 KBUILD_CFLAGS += -Dmalloc=barebox_malloc -Dcalloc=barebox_calloc \
@@ -49,6 +57,7 @@ machdirs := $(patsubst %,arch/sandbox/mach-%/,$(machine-y))
 KBUILD_CPPFLAGS += $(patsubst %,-I$(srctree)/%include,$(machdirs))
 
 archprepare: maketools
+	$(Q)$(MAKE) $(build)=$(HOST_DIR)/um
 
 PHONY += maketools
 
diff --git a/scripts/subarch.include b/scripts/subarch.include
new file mode 100644
index 000000000000..caf3c641b52a
--- /dev/null
+++ b/scripts/subarch.include
@@ -0,0 +1,11 @@
+# SUBARCH tells the usermode build what the underlying arch is.  That is set
+# first, and if a usermode build is happening, the "ARCH=sandbox" 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.
+
+SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
+				  -e s/arm.*/arm/ -e s/sa110/arm/ \
+				  -e s/aarch64.*/arm/ \
+				  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
+				  -e s/riscv.*/riscv/)
-- 
2.39.5