zephyr/Makefile: Allow to adjust heap size from make command line.

zephyr/Makefile

@@ -15,6 +15,10 @@ BOARD ?= qemu_x86
 # Zephyr 1.6.0
 OUTDIR_PREFIX = $(BOARD)
 
+# Default heap size is 16KB, which is on conservative side, to let
+# it build for smaller boards, but it won't be enough for larger
+# applications, and will need to be increased.
+MICROPY_HEAP_SIZE = 16384
 FROZEN_DIR = scripts
 
 # Zephyr (generated) config files - must be defined before include below
@@ -52,7 +56,7 @@ SRC_QSTR += $(SRC_C)
 OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 
 CFLAGS = $(KBUILD_CFLAGS) $(NOSTDINC_FLAGS) $(ZEPHYRINCLUDE) \
-	 -std=gnu99 -DNDEBUG $(INC)
+	 -std=gnu99 -DNDEBUG -DMICROPY_HEAP_SIZE=$(MICROPY_HEAP_SIZE) $(INC)
 
 include ../py/mkrules.mk
 

zephyr/main.c

@@ -58,7 +58,7 @@ void do_str(const char *src, mp_parse_input_kind_t input_kind) {
 }
 
 static char *stack_top;
-static char heap[16 * 1024];
+static char heap[MICROPY_HEAP_SIZE];
 
 int real_main(void) {
     int stack_dummy;

zephyr/mpconfigport.h

@@ -28,6 +28,11 @@
 // Include Zephyr's autoconf.h, which should be made first by Zephyr makefiles
 #include "autoconf.h"
 
+// Usually passed from Makefile
+#ifndef MICROPY_HEAP_SIZE
+#define MICROPY_HEAP_SIZE (16 * 1024)
+#endif
+
 #define MICROPY_STACK_CHECK         (1)
 #define MICROPY_ENABLE_GC           (1)
 #define MICROPY_HELPER_REPL         (1)