zephyr: Implement smart way to access Zephyr config variables.

For this, we first build Z part with libmicropython.a not existing. This
produces autoconf.h with all setiings, but eventually fails on linking
stage due to missing libmicropython.a. We then build MicroPython, which
now can access values in autoconf.h. Then we execute Z build again, which
now succeeds.

zephyr/Makefile

@@ -11,14 +11,18 @@
 
 ARCH ?= x86
 BOARD = qemu_x86
+# Zephyr 1.5.0
+OUTDIR_PREFIX =
+# Zephyr 1.6.0
+#OUTDIR_PREFIX = $(BOARD)
 
 # Zephyr toolchain config is 2-pass, so included twice
 include $(ZEPHYR_BASE)/scripts/Makefile.toolchain.$(ZEPHYR_GCC_VARIANT)
 include $(ZEPHYR_BASE)/scripts/Makefile.toolchain.$(ZEPHYR_GCC_VARIANT)
 
-CFLAGS_arm = -mthumb -mcpu=cortex-m3 -mabi=aapcs -DCONFIG_ARM=y -DCONFIG_ISA_THUMB2=y
+CFLAGS_arm = -mthumb -mcpu=cortex-m3 -mabi=aapcs
 CFLAGS_x86 = -fno-asynchronous-unwind-tables -ffreestanding -fno-stack-protector \
-    -fno-omit-frame-pointer -mpreferred-stack-boundary=2 -mno-sse -march=pentium -DCONFIG_X86=1
+    -fno-omit-frame-pointer -mpreferred-stack-boundary=2 -mno-sse -march=pentium
 CFLAGS_TARGET = $(CFLAGS_$(ARCH))
 
 include ../py/mkenv.mk
@@ -27,6 +31,9 @@ include ../py/py.mk
 INC += -I.
 INC += -I..
 INC += -I$(BUILD)
+INC += -I$(ZEPHYR_BASE)/include -I$(ZEPHYR_BASE) \
+    -Ioutdir/$(OUTDIR_PREFIX)/misc/generated/sysgen \
+    -I$(dir $(Z_AUTOCONF_H))
 
 SRC_C = main.c \
 	uart_core.c \
@@ -49,5 +56,14 @@ all: $(LIBMICROPYTHON)
 qemu: all
 	make -f Makefile.zephyr qemu BOARD=$(BOARD)
 
+Z_AUTOCONF_H = outdir/$(OUTDIR_PREFIX)/include/generated/autoconf.h
+
+$(LIBMICROPYTHON): $(Z_AUTOCONF_H)
+build/genhdr/qstr.i.last: $(Z_AUTOCONF_H)
+
+$(Z_AUTOCONF_H):
+	rm -f $(LIBMICROPYTHON)
+	-make -f Makefile.zephyr BOARD=$(BOARD)
+
 # Clean Zephyr things too
 CLEAN_EXTRA = outdir

zephyr/mpconfigport.h

@@ -46,3 +46,6 @@ typedef long mp_off_t;
 
 #define MICROPY_PORT_ROOT_POINTERS \
     const char *readline_hist[8];
+
+// Include Zephyr's autoconf.h, which should be made first by Zephyr makefiles
+#include "autoconf.h"