==About==
-The main goal of the lwext4 project is to provide ext2/3/4 filesystem
-library for microcontrolers with SD/MMC card support. Ext2/3/4, in my
-opinion is one of the best filesystem for SD/MMC.
+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
==Minimum memory requirements==
-
-=====PROGRAM:=====
- - 20KB
-=====RAM:=====
- - 8KB
-=====STACK:=====
- - 2KB
+* .text: 20KB - 40KB (dependent of feature set chosen)
+* .data: 8KB (minimum 8 x 1KB block cache)
+* .stack: 2KB
==ext2/3/4 vs FAT32==
;ext2/3/4 > FAT32
-* fseek operation on big file in FAT32 is IO heavy
-* ext2/3/4 HTREE directories operations are faster than FAT32
-* ext4 extents makes truncate/remove opertion really fast
+* fast fseek on big file (in FAT32 fseek equals many IO operations)
+* ext2/3/4 HTREE directory operations (like find entry) are faster
+* fast extent big file allocation (truncate/remove)
* more at https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout
;ext2/3/4 < FAT32
==Credits==
-A lot of the implementation of lwext4 was taken from HelenOS:
- http://helenos.org/
-
-Some of ideas and features are based on FreeBSD and Linux implementations.
+The most of the source code of lwext4 was taken from HelenOS:
+* http://helenos.org/
+Some features are based on FreeBSD and Linux implementations.
==Supported ext2/3/4 fs features==
-
-
-;FEATURE_INCOMPAT (unable to mount with unsupported feature):
- compression: no
- filetype: yes
- recover: no (could be ignored)
- journal_dev: no
- meta_bg: yes
- extents: yes
- 64bit: yes
- mmp: no (could be ignored)
- flex_bg: yes
- ea_inode: no
- dirdata: no
- bg_meta_csum: no
- largedir: no
- inline_data: no
-
-;FEATURE_COMPAT (able to mount with unsupported feature):
- dir_prealloc: no
- imagic_inodes: no
- has_journal: no
- ext_attr: no
- resize_inode: no
- dir_index: yes
-
-;FEATURE_RO (able to mount in read only mode):
- sparse_super: yes
- large_file: yes
- btree_dir: yes (obsolete)
- huge_file: yes
- gdt_csum: yes
- dir_nlink: yes
- extra_isize: yes
- quota: no
- bigalloc: no
- metadata_csum: no
-
+;Features incompatible (unable to mount when NOT supported):
+* compression: no
+* filetype: yes
+* recover: no (could be ignored)
+* journal_dev: no
+* meta_bg: yes
+* extents: yes
+* 64bit: yes
+* mmp: no (could be ignored)
+* flex_bg: yes
+* ea_inode: no
+* dirdata: no
+* bg_meta_csum: no
+* largedir: no
+* inline_data: no
+;Features compatible (mount when NOT supported is possible):
+* dir_prealloc: no
+* imagic_inodes: no
+* has_journal: no
+* ext_attr: no (work in progress)
+* resize_inode: no
+* dir_index: yes
+;Features read-only (mount in RO mode when NOT supported):
+* sparse_super: yes
+* large_file: yes
+* btree_dir: yes (obsolete)
+* huge_file: yes
+* gdt_csum: yes
+* dir_nlink: yes
+* extra_isize: yes
+* quota: no
+* bigalloc: no
+* metadata_csum: no (to be done ...)
==Supported filetypes:==
- FIFO: no
- CHARDEV: no
- DIRECTORY: yes
- BLOCKDEV: no
- FILE: yes
- SOFTLINK: no
- SOCKET: no
+* FIFO: no
+* CHARDEV: no
+* DIRECTORY: yes
+* BLOCKDEV: no
+* FILE: yes (hardlinks supported)
+* SOFTLINK: yes
+* SOCKET: no
==Other==
- block_size: 1KB, 2KB, 4KB ... 64KB
- little/big endian architecture support
-
==Project tree==
-
- - blockdev - block devices set, supported blockdevs
- -- filedev - file based block device
- -- io_raw - wiodows IO block device
-
- - demos - demo directory sources
- -- generic - generic demo app, used for development and and debbuging purpose
-
- - lwext4 - internals of the lwext4 library
-
- - toolchain - specific toolchain cmake files
-
- - ext4.h - lwext4 client library header
- - CMakeLists.txt - CMake config file
- - ext_images.7z - ext2/3/4 100MB images
- - fs_test.mk - automatic tests definition
- - Makefile - helper makefile to call cmake
- - readme.mediawiki - yes, you are here ;)
+* blockdev - block devices set, supported blockdev
+* demos - demo directory sources
+* 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 trigger cmake, tests
+* readme.mediawiki - readme file
==Compile: Windows==
-;Tools needed:
+Requirements:
* CMake: http://www.cmake.org/cmake/resources/software.html
* MinGw: http://www.mingw.org/
* GnuWin: http://gnuwin32.sourceforge.net/
==Compile: Linux==
-Tools needed:
- - CMake: http://www.cmake.org/cmake/resources/software.html
+Requirements:
+* CMake: http://www.cmake.org/cmake/resources/software.html
;Create CMake files:
make
make
==Generic demo application==
-
Features:
- - 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
+* 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:
Windows/Linux fileimages:
Linux block devices:
cd build_generic
- generic --in /dev/your_block_device
-
-Usage:
- --i - input file (default = ext2)
- --rws - single R/W size (default = 1024 * 1024)
- --rwc - R/W count (default = 10)
- --cache - 0 static, 1 dynamic (default = 1)
- --dirs - directory test count (default = 0)
- --clean - clean up after test
- --bstat - block device stats
- --sbstat - superblock stats
- --wpart - windows partition mode
-
-==Client-server automatic test suite==
-
-Build:
+ generic -i /dev/your_block_device
+
+==Build and run automatic tests==
+Build and run automatic tests
+Build automatic test tools:
make
cd build_generic
make
-
-Unpack images:
+Uncompress ext/2/3/4 images:
make unpack_images
-
-Run server:
+Run server app for predefined images:
make server_ext2
-
+ make server_ext3
+ make server_ext4
Run tests:
- make all_tests
-
-
-==Cross-Compile==
-
- Toolchain for ARM Cortex-m3/4: https://launchpad.net/gcc-arm-embedded
- Toolchain for Blackfin: http://blackfin.uclinux.org/doku.php
+ make test
+==Cross-Compile standalone library==
Build bf518 library:
make bf518
cd build_bf518
cd build_cortex-m4
make lwext4
-==Ports==
-STM32F429-DISCO USB flash drive Demo
-
-Build STM32F429 Demo:
- make cortex-m4
- cd build_cortex-m4
- make all
-
-==Footprint==
-
- TOOLCHAIN: arm-none-eabi-gcc
- OPT: Os
- OUTPUT:
- text data bss dec hex filename
- 5728 0 0 5728 1660 ext4.c.obj (ex liblwext4.a)
- 2264 0 0 2264 8d8 ext4_balloc.c.obj (ex liblwext4.a)
- 1324 0 0 1324 52c ext4_bcache.c.obj (ex liblwext4.a)
- 936 0 0 936 3a8 ext4_bitmap.c.obj (ex liblwext4.a)
- 2016 0 0 2016 7e0 ext4_blockdev.c.obj (ex liblwext4.a)
- 624 0 0 624 270 ext4_block_group.c.obj (ex liblwext4.a)
- 24 0 4 28 1c ext4_debug.c.obj (ex liblwext4.a)
- 2264 0 0 2264 8d8 ext4_dir.c.obj (ex liblwext4.a)
- 3204 0 0 3204 c84 ext4_dir_idx.c.obj (ex liblwext4.a)
- 3104 0 0 3104 c20 ext4_extent.c.obj (ex liblwext4.a)
- 7360 0 0 7360 1cc0 ext4_fs.c.obj (ex liblwext4.a)
- 2496 0 0 2496 9c0 ext4_hash.c.obj (ex liblwext4.a)
- 684 0 0 684 2ac ext4_ialloc.c.obj (ex liblwext4.a)
- 652 0 0 652 28c ext4_inode.c.obj (ex liblwext4.a)
- 352 0 0 352 160 ext4_super.c.obj (ex liblwext4.a)
-
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projects / lwext4.git / blobdiff