The main goal of the lwext4 project is to provide ext2/3/4 filesystem for microcontrollers. It may be an interesting alternative for traditional MCU filesystem libraries (mostly based on FAT32).
Lwext4 may be used with SD/MMC card, USB flash drive or other block based memory device. However it is not good for flash memory–based storage devices.
Code is also available on github: https://github.com/gkostka/lwext4
Feel free to contact me: kostka.grzegorz@gmail.com
The most of the source code of lwext4 was taken from HelenOS:
Some features are based on FreeBSD and Linux implementations.KaHo Ng (https://github.com/ngkaho1234):
- advanced extents implementation
- xattr support
- metadata checksum suport
- many bugfixes & improvements
- filetypes: regular, directories, softlinks
- support for hardlinks
- multiple blocksize supported: 1KB, 2KB, 4KB ... 64KB
- little/big endian architectures supported
- multiple configurations (ext2/ext3/ext4)
- only C standard library dependency
- various CPU architectures supported (x86/64, cortex-mX, msp430 ...)
- small memory footprint
- Memory footprint (for cortex-m4):
- .text: 20KB - 40KB
- .data: 8KB (minimum 8 x 1KB block cache)
- .stack: 2KB
- Features incompatible:
- compression: no
- filetype: yes
- recover: no
- journal_dev: no
- meta_bg: yes
- extents: yes
- 64bit: yes
- mmp: no
- flex_bg: yes
- ea_inode: no
- dirdata: no
- bg_meta_csum: no
- largedir: no
- inline_data: no
- Features compatible:
- dir_prealloc: no
- imagic_inodes: no
- has_journal: no
- ext_attr: yes
- resize_inode: no
- dir_index: yes
- Features read-only:
- sparse_super: yes
- large_file: yes
- btree_dir: yes
- huge_file: yes
- gdt_csum: yes
- dir_nlink: yes
- extra_isize: yes
- quota: no
- bigalloc: no
- metadata_csum: yes
- blockdev - block devices set, supported blockdev
- demos - demo directory sources
- fs_test - test suite
- lwext4 - internals of the lwext4 library
- toolchain - specific toolchain cmake files
- CMakeLists.txt - CMake config file
- ext_images.7z - compressed ext2/3/4 100MB images
- fs_test.mk - automatic tests definitions
- Makefile - helper makefile to generate cmake and run test suite
- readme.mediawiki - readme file
Windows:
- CMake: http://www.cmake.org/cmake/resources/software.html
- MinGw: http://www.mingw.org/
- GnuWin: http://gnuwin32.sourceforge.net/
- CMake, make, gcc
- Generate makefiles:
make
- Compile
cd build_generic make
Simple lwext4 library presentation:
- load ext2/3/4 images
- load linux block device with ext2/3/4 part
- load windows volume with ext2/3/4 filesystem
- directory speed test
- file write/read speed test
cd build_generic generic -i ext_images/ext2 generic -i ext_images/ext3 generic -i ext_images/ext4
Build and run automatic tests Build automatic test tools:
make cd build_generic make
Uncompress ext/2/3/4 images:
make unpack_images
Run server for one of the image file:
make server_ext2 make server_ext3 make server_ext4
Execute tests:
make test
Toolchains needed:
- arm-none-eabi-gcc for cortex-mX
- avr-gcc for avr
- bfin-elf-gcc for bfin
- msp430-gcc for msp430
make bf518 cd build_bf518 make lwext4
Build avrxmega7 library:
make avrxmega7 cd build_avrxmega7 make lwext4
Build cortex-m0 library:
make cortex-m0 cd build_cortex-m0 make lwext4
Build cortex-m3 library:
make cortex-m3 cd build_cortex-m3 make lwext4
Build cortex-m4 library:
make cortex-m4 cd build_cortex-m4 make lwext4