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==About==
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The main goal of the lwext4 project is to provide ext2/3/4 filesystem
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library for microcontrolers with SD/MMC card support. Ext2/3/4, in my
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opinion is one of the best filesystem for SD/MMC.
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kostka.grzegorz@gmail.com
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==Minimum memory requirements==
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=====PROGRAM:=====
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- 20KB
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=====RAM:=====
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- 8KB
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=====STACK:=====
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- 2KB
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==ext2/3/4 vs FAT32==
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;ext2/3/4 > FAT32
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* fseek operation on big file in FAT32 is IO heavy
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* ext2/3/4 HTREE directories operations are faster than FAT32
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* ext4 extents makes truncate/remove opertion really fast
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* more at https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout
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;ext2/3/4 < FAT32
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* FAT32 has smaller footprint
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==Credits==
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A lot of the implementation of lwext4 was taken from HelenOS:
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http://helenos.org/
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Some of ideas and features are based on FreeBSD and Linux implementations.
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==Supported ext2/3/4 fs features==
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;FEATURE_INCOMPAT (unable to mount with unsupported feature):
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COMPRESSION: no
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FILETYPE: yes
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RECOVER: no
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JOURNAL_DEV: no
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META_BG: no
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EXTENTS: yes
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64BIT: yes
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MMP: no
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FLEX_BG: no
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EA_INODE: no
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DIRDATA: no
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;FEATURE_COMPAT (able to mount with unsupported feature):
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DIR_PREALLOC: no
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IMAGIC_INODES: no
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HAS_JOURNAL: no
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EXT_ATTR: no
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RESIZE_INODE: no
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DIR_INDEX: yes
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;FEATURE_RO (able to mount in read only mode):
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SPARSE_SUPER: yes
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LARGE_FILE: yes
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BTREE_DIR: no
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HUGE_FILE: yes
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GDT_CSUM: yes
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DIR_NLINK: yes
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EXTRA_ISIZE: yes
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==Supported filetypes:==
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FIFO: no
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CHARDEV: no
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DIRECTORY: yes
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BLOCKDEV: no
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FILE: yes
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SOFTLINK: no
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SOCKET: no
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==Other==
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- block_size: 1KB, 2KB, 4KB ... 64KB
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- little/big endian architecture support
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==Project tree==
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- blockdev - block devices set, supported blockdevs
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-- filedev - file based block device
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-- io_raw - wiodows IO block device
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- demos - demo directory sources
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-- generic - generic demo app, used for development and and debbuging purpose
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- lwext4 - internals of the lwext4 library
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- toolchain - specific toolchain cmake files
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- ext4.h - lwext4 client library header
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- CMakeLists.txt - CMake config file
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- ext_images.7z - ext2/3/4 100MB images
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- Makefile - helper makefile to call cmake
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- readme.mediawiki - yes, you are here ;)
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==Compile: Windows==
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;Tools needed:
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* CMake: http://www.cmake.org/cmake/resources/software.html
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* MinGw: http://www.mingw.org/
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* GnuWin: http://gnuwin32.sourceforge.net/
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;Create CMake files:
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make
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;Remove CMake files:
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clean
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;Build
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cd build_generic
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make
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==Compile: Linux==
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Tools needed:
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- CMake: http://www.cmake.org/cmake/resources/software.html
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;Create CMake files:
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make
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;Remove CMake files:
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clean
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;Build
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cd build_generic
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make
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==Generic demo applicarion==
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Features:
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- load ext2/3/4 images
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- load linux block device with ext2/3/4 part
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- load windows volume with ext2/3/4 filesystem
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- directory speed test
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- file write/read speed test
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How to use:
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Windows/Linux fileimages:
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cd build_generic
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fileimage_demo --in ext2
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Windows volumes:
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cd build_generic
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fileimage_demo --in I: --wpart
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Linux block devices:
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cd build_generic
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fileimage_demo --in /dev/your_block_device
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Usage:
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--i - input file (default = ext2)
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--rws - single R/W size (default = 1024 * 1024)
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--rwc - R/W count (default = 10)
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--cache - 0 static, 1 dynamic (default = 1)
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--dirs - directory test count (default = 0)
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--clean - clean up after test
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--bstat - block device stats
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--sbstat - superblock stats
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--wpart - windows partition mode
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==Cross-Compile==
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Toolchain for ARM Cortex-m3/4: https://launchpad.net/gcc-arm-embedded
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Toolchain for Blackfin: http://blackfin.uclinux.org/doku.php
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Build bf518 library:
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make bf518
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Build cortex-m3 library:
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make cortex-m3
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Build cortex-m4 library:
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make cortex-m4
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==Ports==
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*Blackfin BF518 EZKIT SD Card Demo: TBD
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*STM32F4-Discovery SD Card Demo: TBD
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==Footprint==
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TBD
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