ref: b31faab0fab65e98b1700622427e29555d8197d1
parent: 67234632535b947ed8430f8603052e6651bd1ec6
author: gkostka <kostka.grzegorz@gmail.com>
date: Mon Nov 11 09:34:55 EST 2013
Update readme file.
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+==About lwext4==
+
+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.
+
+kostka.grzegorz@gmail.com
+
+==Minimum memory requirements==
+
+=====PROGRAM:=====
+ - 20KB
+=====RAM:=====
+ - 8KB
+=====STACK:=====
+ - 1KB-2KB (not tested yet)
+
+
+==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
+* more at https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout
+
+;ext2/3/4 < FAT32
+* FAT32 has smaller footprint
+
+==Credits lwext4==
+
+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.
+
+==lwext4 supported/unsupported ext2/3/4 fs features==
+
+;FEATURE_INCOMPAT (unable to mount with unsupported feature):
+ COMPRESSION: no
+ FILETYPE: yes
+ RECOVER: no
+ JOURNAL_DEV: no
+ META_BG: no
+ EXTENTS: yes
+ 64BIT: yes
+ MMP: no
+ FLEX_BG: no
+ EA_INODE: no
+ DIRDATA: no
+
+;FEATURE_INCOMPAT (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 with unsupported feature):
+ SPARSE_SUPER: yes
+ LARGE_FILE: yes
+ BTREE_DIR: no
+ HUGE_FILE: yes
+ GDT_CSUM: yes
+ DIR_NLINK: yes
+ EXTRA_ISIZE: yes
+
+==Supported filetypes:==
+ FIFO: no
+ CHARDEV: no
+ DIRECTORY: yes
+ BLOCKDEV: no
+ FILE: yes
+ SOFTLINK: no
+ SOCKET: no
+
+==Other:==
+ - block_size: 1KB, 2KB, 4KB ... 64KB
+ - little/big endian architecture support
+
+
+==lwext4 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
+ - Makefile - helper makefile to call cmake
+ - readme.mediawiki - yes, you are here ;)
+
+==lwext4 compile Windows==
+;Tools needed:
+* CMake: http://www.cmake.org/cmake/resources/software.html
+* MinGw: http://www.mingw.org/
+* GnuWin: http://gnuwin32.sourceforge.net/
+
+;Create CMake files:
+ make
+
+;Remove CMake files:
+ clean
+
+;Build
+ cd build_generic
+ make
+
+==lwext4 compile Linux==
+
+Tools needed:
+ - CMake: http://www.cmake.org/cmake/resources/software.html
+
+;Create CMake files:
+ make
+
+;Remove CMake files:
+ clean
+
+;Build
+ cd build_generic
+ make
+
+==lwext4 generic demo app==
+
+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
+
+How to use:
+Windows/Linux fileimages:
+ cd build_generic
+ fileimage_demo --in ext2
+
+Windows volumes:
+ cd build_generic
+ fileimage_demo --in I: --wpart
+
+Linux block devices:
+ cd build_generic
+ fileimage_demo --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
+
+
+==lwext4 compile Cross==
+
+Toolchain for ARM Cortex-m3/4: https://launchpad.net/gcc-arm-embedded
+Toolchain for Blackfin: http://blackfin.uclinux.org/doku.php
+
+Build bf158 library:
+ make bf518
+
+Build cortex-m3 library:
+ make cortex-m3
+
+Build cortex-m4 library:
+ make cortex-m4
+
+==lwext4 ports==
+ -Blackfin BF518 EZKIT SD Card Demo: TBD
+ -STM32F4-Discovery SD Card Demo: TBD
+
+==lwext4 footprint==
+
+TBD
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