==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