qemu: Add basic ROMFS support.

This commit adds basic ROMFS support.  This helps with running tests since
mpremote mount is too slow with big files.

To be configured per-board, and then run with:

    $ make QEMU_ROMFS_IMG0=image.romfs ...

Signed-off-by: iabdalkader <i.abdalkader@gmail.com>

Author: iabdalkader

ports/qemu/Makefile

@@ -158,6 +158,14 @@ QEMU_SYSTEM = $(QEMU_BASE)$(QEMU_ARCH)
 QEMU_ARGS += -machine $(QEMU_MACHINE) -nographic -monitor null -semihosting
 QEMU_ARGS += $(QEMU_EXTRA)
 
+# Load ROMFS images into emulated memory if configured.
+ifneq ($(QEMU_ROMFS_IMG0),)
+QEMU_ARGS += -device loader,file=$(QEMU_ROMFS_IMG0),addr=$(MICROPY_HW_ROMFS_PART0_START),force-raw=on
+endif
+ifneq ($(QEMU_ROMFS_IMG1),)
+QEMU_ARGS += -device loader,file=$(QEMU_ROMFS_IMG1),addr=$(MICROPY_HW_ROMFS_PART1_START),force-raw=on
+endif
+
 # Specifying QEMU_DEBUG=1 will block qemu until a debugger is connected.
 ifeq ($(QEMU_DEBUG),1)
 QEMU_DEBUG_ARGS ?= -s
@@ -209,6 +217,7 @@ SRC_C += \
 	main.c \
 	uart.c \
 	mphalport.c \
+	vfs_rom_ioctl.c \
 	shared/libc/string0.c \
 	shared/readline/readline.c \
 	shared/runtime/interrupt_char.c \

ports/qemu/README.md

@@ -166,6 +166,7 @@ The following options can be specified on the `make` command line:
 - `QEMU_DEBUG_ARGS`: defaults to `-s` (gdb on TCP port 1234), but can be overridden
   with different qemu gdb arguments.
 - `QEMU_DEBUG_EXTRA`: extra options to pass to qemu when `QEMU_DEBUG=1` is used.
+- `QEMU_ROMFS_IMG<n>`: pass in romfs image to be loaded by qemu (if enabled by the board).
 - `TEST_NATMODS`: pass an optional list of space-separated names of natmods to test,
   so only the given subset of example natmods will be used by `test_natmod` (for
   example, `make test_natmod TEST_NATMODS="btree heapq re"`).

ports/qemu/mpconfigport.h

@@ -67,7 +67,7 @@
 #define MICROPY_PY_MACHINE_PIN_BASE (1)
 #define MICROPY_VFS                 (1)
 #define MICROPY_VFS_ROM             (1)
-#define MICROPY_VFS_ROM_IOCTL       (0)
+#define MICROPY_VFS_ROM_IOCTL       (MICROPY_HW_ROMFS_ENABLE_PART0 || MICROPY_HW_ROMFS_ENABLE_PART1)
 
 // type definitions for the specific machine
 

ports/qemu/vfs_rom_ioctl.c

@@ -0,0 +1,83 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2025 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/obj.h"
+#include "py/objarray.h"
+#include "py/mperrno.h"
+#include "extmod/vfs.h"
+
+#if MICROPY_VFS_ROM_IOCTL
+
+#if MICROPY_HW_ROMFS_ENABLE_PART0 && !defined(MICROPY_HW_ROMFS_PART0_START)
+#define MICROPY_HW_ROMFS_PART0_START (uintptr_t)(&_micropy_hw_romfs_part0_start)
+#define MICROPY_HW_ROMFS_PART0_SIZE (uintptr_t)(&_micropy_hw_romfs_part0_size)
+extern uint8_t _micropy_hw_romfs_part0_start;
+extern uint8_t _micropy_hw_romfs_part0_size;
+#endif
+
+#if MICROPY_HW_ROMFS_ENABLE_PART1 && !defined(MICROPY_HW_ROMFS_PART1_START)
+#define MICROPY_HW_ROMFS_PART1_START (uintptr_t)(&_micropy_hw_romfs_part1_start)
+#define MICROPY_HW_ROMFS_PART1_SIZE (uintptr_t)(&_micropy_hw_romfs_part1_size)
+extern uint8_t _micropy_hw_romfs_part1_start;
+extern uint8_t _micropy_hw_romfs_part1_size;
+#endif
+
+#define ROMFS_MEMORYVIEW(base, size) {{&mp_type_memoryview}, 'B', 0, (size), (void *)(base)}
+
+static const mp_obj_array_t romfs_obj_table[] = {
+    #if MICROPY_HW_ROMFS_ENABLE_PART0
+    ROMFS_MEMORYVIEW(MICROPY_HW_ROMFS_PART0_START, MICROPY_HW_ROMFS_PART0_SIZE),
+    #endif
+    #if MICROPY_HW_ROMFS_ENABLE_PART1
+    ROMFS_MEMORYVIEW(MICROPY_HW_ROMFS_PART1_START, MICROPY_HW_ROMFS_PART1_SIZE),
+    #endif
+};
+
+mp_obj_t mp_vfs_rom_ioctl(size_t n_args, const mp_obj_t *args) {
+    mp_int_t cmd = mp_obj_get_int(args[0]);
+    if (cmd == MP_VFS_ROM_IOCTL_GET_NUMBER_OF_SEGMENTS) {
+        return MP_OBJ_NEW_SMALL_INT(MP_ARRAY_SIZE(romfs_obj_table));
+    }
+
+    if (n_args < 2) {
+        return MP_OBJ_NEW_SMALL_INT(-MP_EINVAL);
+    }
+
+    mp_int_t romfs_id = mp_obj_get_int(args[1]);
+    if (!(0 <= romfs_id && romfs_id < MP_ARRAY_SIZE(romfs_obj_table))) {
+        return MP_OBJ_NEW_SMALL_INT(-MP_EINVAL);
+    }
+
+    if (cmd == MP_VFS_ROM_IOCTL_GET_SEGMENT) {
+        // Return the ROMFS memoryview object.
+        const mp_obj_array_t *romfs_obj = &romfs_obj_table[romfs_id];
+        return MP_OBJ_FROM_PTR(romfs_obj);
+    }
+
+    return MP_OBJ_NEW_SMALL_INT(-MP_EINVAL);
+}
+
+#endif // MICROPY_VFS_ROM_IOCTL