ref: 2df08d93f8dda03f5cf3bb9c6928626540b9ef32
dir: lwext4/README.md
[](https://travis-ci.org/gkostka/lwext4)  About ===== 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 Credits ===== The most of the source code of lwext4 was taken from HelenOS: * http://helenos.org/ Some features are based on FreeBSD and Linux implementations. KaHo Ng (https://github.com/ngkaho1234): * advanced extents implementation * xattr support * metadata checksum support * journal recovery * many bugfixes & improvements fuse-lwext4 project: * https://github.com/ngkaho1234/fuse-lwext4 Features ===== * 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 Supported ext2/3/4 features ===== 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: yes (in progress) * 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 Project tree ===== * blockdev - block devices set, supported blockdev * fs_test - test suite, mkfs and demo application * 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 Compile ===== Dependencies ------------ * Windows Download MSYS-2: https://sourceforge.net/projects/msys2/ Install required packages is MSYS2 Shell package manager: ```bash pacman -S make gcc cmake p7zip ``` * Linux Package installation (Debian): ```bash apt-get install make gcc cmake p7zip ``` Compile & install tools ------------ ```bash make generic cd build_generic make sudo make install ``` lwext4-generic demo application ===== Simple lwext4 library test application: * 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 How to use for images/blockdevices: ```bash lwext4-generic -i ext_images/ext2 lwext4-generic -i ext_images/ext3 lwext4-generic -i ext_images/ext4 ``` Show full option set: ```bash lwext4-generic --help ``` Run automatic tests ===== Execute tests for 100MB unpacked images: ```bash make test ``` Execute tests for autogenerated 1GB images (only on Linux targets) + fsck: ```bash make test_all ``` Using lwext4-mkfs tool ===== It is possible to create ext2/3/4 partition by internal library tool. Generate empty file (1GB): ```bash dd if=/dev/zero of=ext_image bs=1M count=1024 ``` Create ext2 partition: ```bash lwext4-mkfs -i ext_image -e 2 ``` Create ext3 partition: ```bash lwext4-mkfs -i ext_image -e 3 ``` Create ext4 partition: ```bash lwext4-mkfs -i ext_image -e 4 ``` Show full option set: ```bash lwext4-mkfs --help ``` Cross compile standalone library ===== Toolchains needed: ------------ * arm-none-eabi-gcc for cortex-mX * avr-gcc for avr * bfin-elf-gcc for bfin * msp430-gcc for msp430 Build bf518 library: ------------ ```bash make bf518 cd build_bf518 make lwext4 ``` Build avrxmega7 library: ------------ ```bash make avrxmega7 cd build_avrxmega7 make lwext4 ``` Build cortex-m0 library: ------------ ```bash make cortex-m0 cd build_cortex-m0 make lwext4 ``` Build cortex-m3 library: ------------ ```bash make cortex-m3 cd build_cortex-m3 make lwext4 ``` Build cortex-m4 library: ------------ ```bash make cortex-m4 cd build_cortex-m4 make lwext4 ```