interpreters/python: add wrapper to initialize Python

This wrapper application checks if the Python's modules are already
mounted (and mounts them, if not), sets the necessary environment
variables and, then, runs the Python interpreter.

Author: tmedicci

interpreters/python/Kconfig

@@ -27,7 +27,7 @@ config INTERPRETER_CPYTHON_STACKSIZE
 
 config INTERPRETER_CPYTHON_PRIORITY
 	int "CPython task priority"
-	default 150
+	default 100
 	---help---
 		This is the priority of the CPython task.
 
@@ -37,22 +37,4 @@ config INTERPRETER_CPYTHON_PROGNAME
 	---help---
 		This is the name of the program that will be used from the nsh.
 
-config INTERPRETER_CPYTHON_MOUNT_MODULES_STACKSIZE
-	int "CPython's Modules Mount stack size"
-	default 4096
-	---help---
-		This is the stack size allocated when the CPython's Modules Mount task runs.
-
-config INTERPRETER_CPYTHON_MOUNT_MODULES_PRIORITY
-	int "CPython's Modules Mount task priority"
-	default 150
-	---help---
-		This is the priority of the CPython's Modules Mount task.
-
-config INTERPRETER_CPYTHON_MOUNT_MODULES_PROGNAME
-	string "CPython's Modules Mount app name"
-	default "python_mount_modules"
-	---help---
-		This is the name of the program that will be used from the nsh.
-
 endif

interpreters/python/Makefile

@@ -175,13 +175,7 @@ PROGNAME  += $(CONFIG_INTERPRETER_CPYTHON_PROGNAME)
 PRIORITY  += $(CONFIG_INTERPRETER_CPYTHON_PRIORITY)
 STACKSIZE += $(CONFIG_INTERPRETER_CPYTHON_STACKSIZE)
 
-MAINSRC += python.c
-
-PROGNAME  += $(CONFIG_INTERPRETER_CPYTHON_MOUNT_MODULES_PROGNAME)
-PRIORITY  += $(CONFIG_INTERPRETER_CPYTHON_MOUNT_MODULES_PRIORITY)
-STACKSIZE += $(CONFIG_INTERPRETER_CPYTHON_MOUNT_MODULES_STACKSIZE)
-
-MAINSRC += mount_modules.c
+MAINSRC += python_wrapper.c
 
 checkgenromfs:
 	@genromfs -h 1>/dev/null 2>&1 || { \

interpreters/python/mount_modules.c renamed to interpreters/python/python_wrapper.c

@@ -1,5 +1,5 @@
 /****************************************************************************
- * apps/interpreters/python/mount_modules.c
+ * apps/interpreters/python/python_wrapper.c
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -41,11 +41,14 @@
 #include <fcntl.h>
 #include <dirent.h>
 #include <errno.h>
+#include <debug.h>
 
 #include <nuttx/drivers/ramdisk.h>
 
 #include "romfs_cpython_modules.h"
 
+#include "Python.h"
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -61,7 +64,7 @@
 #endif
 
 #ifndef CONFIG_CPYTHON_ROMFS_MOUNTPOINT
-#  define CONFIG_CPYTHON_ROMFS_MOUNTPOINT "/usr/local/lib/"
+#  define CONFIG_CPYTHON_ROMFS_MOUNTPOINT "/usr/local/lib"
 #endif
 
 #ifdef CONFIG_DISABLE_MOUNTPOINT
@@ -85,24 +88,70 @@
  * Private Data
  ****************************************************************************/
 
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
+/* _PyRuntime occupies around 100kB of RAM in .data region, making it hard to
+ * fit the interpreter into the available static RAM. Some devices may have
+ * more RAM available on external PSRAM modules that requires to be properly
+ * initialized before reading/writing data to it. Thus, _PyRuntime can be
+ * moved to bss section and initialized before Python interpreter is started.
+ */
+
+extern void _PyRuntime_Early_Init(void);
 
 /****************************************************************************
- * Public Functions
+ * Private Functions
  ****************************************************************************/
 
 /****************************************************************************
- * Name: mount_modules
+ * Name: check_and_mount_romfs
+ *
+ * Description:
+ *   Check if the ROMFS is already mounted, and if not, mount it.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Value:
+ *   0 on success, 1 on failure
+ *
  ****************************************************************************/
 
-int main(int argc, FAR char *argv[])
+static int check_and_mount_romfs(void)
 {
-  int ret;
+  int ret = OK;
   struct boardioc_romdisk_s desc;
+  FILE *fp;
+  char line[256];
+  int is_mounted = 0;
+
+  /* Check if the device is already mounted */
 
-  /* Create a RAM disk for the test */
+  fp = fopen("/proc/fs/mount", "r");
+  if (fp == NULL)
+    {
+      printf("ERROR: Failed to open /proc/fs/mount\n");
+      UNUSED(desc);
+      return ret = ERROR;
+    }
+
+  while (fgets(line, sizeof(line), fp))
+    {
+      if (strstr(line, CONFIG_CPYTHON_ROMFS_MOUNTPOINT) != NULL)
+        {
+          is_mounted = 1;
+          break;
+        }
+    }
+
+  fclose(fp);
+
+  if (is_mounted)
+    {
+      _info("Device is already mounted at %s\n", CONFIG_CPYTHON_ROMFS_MOUNTPOINT);
+      UNUSED(desc);
+      return ret;
+    }
+
+  /* Create a RAM disk */
 
   desc.minor    = CONFIG_CPYTHON_ROMFS_RAMDEVNO;            /* Minor device number of the ROM disk. */
   desc.nsectors = NSECTORS(romfs_cpython_modules_img_len);  /* The number of sectors in the ROM disk */
@@ -119,8 +168,8 @@ int main(int argc, FAR char *argv[])
 
   /* Mount the test file system */
 
-  printf("Mounting ROMFS filesystem at target=%s with source=%s\n",
-         CONFIG_CPYTHON_ROMFS_MOUNTPOINT, MOUNT_DEVNAME);
+  _info("Mounting ROMFS filesystem at target=%s with source=%s\n",
+        CONFIG_CPYTHON_ROMFS_MOUNTPOINT, MOUNT_DEVNAME);
 
   ret = mount(MOUNT_DEVNAME, CONFIG_CPYTHON_ROMFS_MOUNTPOINT, "romfs",
               MS_RDONLY, NULL);
@@ -132,3 +181,30 @@ int main(int argc, FAR char *argv[])
 
   return 0;
 }
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: python_wrapper_main
+ ****************************************************************************/
+
+int main(int argc, FAR char *argv[])
+{
+  int ret;
+
+  ret = check_and_mount_romfs();
+  if (ret != 0)
+    {
+      return ret;
+    }
+
+  _PyRuntime_Early_Init();
+
+  setenv("PYTHONHOME", "/usr/local", 1);
+
+  setenv("PYTHON_BASIC_REPL", "1", 1);
+
+  return Py_BytesMain(argc, argv);
+}