micropython · dpgeorge · Aug 22, 2025 · Aug 15, 2025 · Aug 15, 2025
diff --git a/examples/embedding/mpconfigport.h b/examples/embedding/mpconfigport.h
@@ -13,3 +13,4 @@
 #define MICROPY_ENABLE_COMPILER                 (1)
 #define MICROPY_ENABLE_GC                       (1)
 #define MICROPY_PY_GC                           (1)
+#define MICROPY_PY_SYS                          (0)
diff --git a/ports/bare-arm/mpconfigport.h b/ports/bare-arm/mpconfigport.h
@@ -37,6 +37,9 @@
 // Python internal features
 #define MICROPY_ERROR_REPORTING                 (MICROPY_ERROR_REPORTING_NONE)
 
+// Fine control over Python builtins, classes, modules, etc.
+#define MICROPY_PY_SYS                          (0)
+
 // Type definitions for the specific machine
 
 typedef int32_t mp_int_t; // must be pointer size

diff --git a/ports/minimal/mpconfigport.h b/ports/minimal/mpconfigport.h
@@ -21,6 +21,12 @@
 // Use the minimum headroom in the chunk allocator for parse nodes.
 #define MICROPY_ALLOC_PARSE_CHUNK_INIT    (16)
 
+// Disable all optional sys module features.
+#define MICROPY_PY_SYS_MODULES            (0)
+#define MICROPY_PY_SYS_EXIT               (0)
+#define MICROPY_PY_SYS_PATH               (0)
+#define MICROPY_PY_SYS_ARGV               (0)
+
 // type definitions for the specific machine
 
 typedef intptr_t mp_int_t; // must be pointer size

diff --git a/ports/nrf/mpconfigport.h b/ports/nrf/mpconfigport.h
@@ -289,7 +289,6 @@
 #define MICROPY_PY_GENERATOR_PEND_THROW       (1)
 #define MICROPY_PY_MATH                       (1)
 #define MICROPY_PY_STRUCT                     (1)
-#define MICROPY_PY_SYS                        (1)
 #define MICROPY_PY_SYS_PATH_ARGV_DEFAULTS     (1)
 #endif
 

diff --git a/ports/powerpc/mpconfigport.h b/ports/powerpc/mpconfigport.h
@@ -81,7 +81,6 @@
 #define MICROPY_PY_CMATH            (0)
 #define MICROPY_PY_IO               (0)
 #define MICROPY_PY_STRUCT           (1)
-#define MICROPY_PY_SYS              (1)
 #define MICROPY_MODULE_FROZEN_MPY   (1)
 #define MICROPY_CPYTHON_COMPAT      (0)
 #define MICROPY_LONGINT_IMPL        (MICROPY_LONGINT_IMPL_MPZ)

diff --git a/ports/unix/variants/minimal/mpconfigvariant.h b/ports/unix/variants/minimal/mpconfigvariant.h
@@ -61,6 +61,5 @@
 #define MICROPY_PY_BUILTINS_RANGE_ATTRS (1)
 #define MICROPY_PY_GENERATOR_PEND_THROW (1)
 
-// Enable just the sys and os built-in modules.
-#define MICROPY_PY_SYS (1)
+// Add just the os built-in module.
 #define MICROPY_PY_OS (1)
diff --git a/ports/zephyr/mpconfigport_minimal.h b/ports/zephyr/mpconfigport_minimal.h
@@ -59,7 +59,6 @@
 #define MICROPY_PY_BUILTINS_STR_OP_MODULO (1)
 #define MICROPY_PY_BUILTINS_BYTEARRAY (1)
 #define MICROPY_PY_BUILTINS_DICT_FROMKEYS (1)
-#define MICROPY_PY_SYS              (1)
 
 #ifdef CONFIG_BOARD
 #define MICROPY_HW_BOARD_NAME "zephyr-" CONFIG_BOARD

diff --git a/py/builtinimport.c b/py/builtinimport.c
@@ -116,7 +116,7 @@ static mp_import_stat_t stat_module(vstr_t *path) {
 // path (i.e. "<entry>/mod_name(.py)").
 static mp_import_stat_t stat_top_level(qstr mod_name, vstr_t *dest) {
     DEBUG_printf("stat_top_level: '%s'\n", qstr_str(mod_name));
-    #if MICROPY_PY_SYS
+    #if MICROPY_PY_SYS && MICROPY_PY_SYS_PATH
     size_t path_num;
     mp_obj_t *path_items;
     mp_obj_get_array(mp_sys_path, &path_num, &path_items);
@@ -367,7 +367,7 @@ static mp_obj_t process_import_at_level(qstr full_mod_name, qstr level_mod_name,
     // Immediately return if the module at this level is already loaded.
     mp_map_elem_t *elem;
 
-    #if MICROPY_PY_SYS
+    #if MICROPY_PY_SYS && MICROPY_PY_SYS_PATH
     // If sys.path is empty, the intention is to force using a built-in. This
     // means we should also ignore any loaded modules with the same name
     // which may have come from the filesystem.

diff --git a/py/mpconfig.h b/py/mpconfig.h
@@ -1610,7 +1610,7 @@ typedef time_t mp_timestamp_t;
 
 // Whether to provide "sys" module
 #ifndef MICROPY_PY_SYS
-#define MICROPY_PY_SYS (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
+#define MICROPY_PY_SYS (1)
 #endif
 
 // Whether to initialise "sys.path" and "sys.argv" to their defaults in mp_init()