romfs — ROMFS helper utilities

The romfs module provides helper utilities for inspecting the read-only filesystem (ROMFS) that the OpenMV firmware mounts at /rom. See Working with ROMFS for an end-to-end description of the ROMFS filesystem itself, how images are built and deployed, and the underlying vfs.VfsRom / vfs.rom_ioctl() APIs.

This module focuses on the physical layout of an already-mounted ROMFS rather than its filesystem semantics. Because .mpy bytecode files in a ROMFS are executed directly from flash (memory-mapped, zero copy), MicroPython needs each file’s payload to be aligned to a sufficient boundary – typically 4 bytes for plain .mpy files and up to 16 bytes when a file contains native-code blobs or aligned data references. ls_romfs() reports the address, size and largest power-of-two alignment of every file so a deployed image can be spot-checked from the REPL before relying on zero-copy imports.

Functions

romfs.ls_romfs() → None

Lists every file present in the ROMFS mounted at /rom and prints diagnostic information about each entry to stdout.

For each file, the following information is printed:

• addr: The memory address of the file’s data, masked to 28 bits and formatted as an 8-digit hexadecimal value.

• size: The size of the file in bytes, obtained from the length of a memoryview of the open file.

• alignment: The largest power-of-two alignment (checked against 128, 64, 32, 16, 8, 4) that the file’s address satisfies. If the address is not aligned to any of these boundaries, NOT aligned is printed instead.

• name: The file name within /rom.

This function takes no arguments and returns None.