32bit Linux ext2 file system driver (EXT2 IFS)

[$Header: d:\\32bits\\ext2-os2\\doc\\ext2-os2\\rcs\\README,v 1.7 1997/03/15 17:06:48 Willm Exp $] ╔═══════════════════════════════════════════════════════════════════════╗ ║ 32 bits Linux ext2 file system driver for OS/2 WARP - Allows OS/2 to ║ ║ access your Linux ext2fs partitions as normal drive letters. ║ ║ Copyright (C) 1995, 1996, 1997 Matthieu WILLM (willm@ibm.net) ║ ║ ║ ║ This program is free software; you can redistribute it and/or modify ║ ║ it under the terms of the GNU General Public License as published by ║ ║ the Free Software Foundation; either version 2 of the License, or ║ ║ (at your option) any later version. ║ ║ ║ ║ This program is distributed in the hope that it will be useful, ║ ║ but WITHOUT ANY WARRANTY; without even the implied warranty of ║ ║ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ║ ║ GNU General Public License for more details. ║ ║ ║ ║ You should have received a copy of the GNU General Public License ║ ║ along with this program; if not, write to the Free Software ║ ║ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. ║ ╚═══════════════════════════════════════════════════════════════════════╝ EXT2-OS2 VERSION 2.40 (32 BITS EDITION) WHAT IS EXT2-OS2 ? ------------------- ext2-os2.ifs is a file system driver that allows OS/2 to seamlessly access Linux native partitions (ext2fs partitions) in both read and write modes. Once installed, Linux partitions appear as standard OS/2 drive letters, one per Linux partition. It is a port of the original Linux ext2fs kernel code. ext2-os2 can even be used without Linux, as it can format or check ext2 file systems directly from OS/2. This can be useful for people who need huge cache sizes, for large compilations for instance ; it can also be useful for people wanting long file names on removable media. INSTALLATION AND USAGE INSTRUCTIONS : ------------------------------------ Please consult the online help file (ext2-os2.inf) for IMPORTANT installation and configuration instructions. Please read the documentation BEFORE installing the driver !! A HTML version of the documentation is also available (ext2-os2.htm) This HTML version has been produced from the IPF version with IBM Hyperwise. It can be viewed with any good web browser, such as the WebExplorer included in the OS/2 Bonus Pack. *********************************************** ***** IMPORTANT WARNING - READ THIS FIRST ***** *********************************************** ext2-os2 is a FILE SYSTEM DRIVER. Being a driver it runs at the most privileged level of the OS/2 operating system, known as "kernel mode". IN KERNEL MODE THERE IS NO MORE CRASH PROTECTION. It means that if a bug occurs in the driver IT CAN CAUSE A HANG OR A SYSTEM HALT, AND THUS CAN CAUSE LOSS OF DATA. - I STRONGLY SUGGEST YOU TO MAKE A BACKUP OF ALL YOUR DATA (EVEN IF THEY ARE NOT LOCATED ON A LINUX PARTITION) PRIOR TO USE THIS DRIVER. - DON'T USE THIS DRIVER ON A PRODUCTION MACHINE, OR IF YOU MANIPULATE CRITICAL DATA. - IF HUMAN LIFE DEPENDS ON YOUR SYSTEM, DON'T INSTALL THIS DRIVER ON IT. - USE IT AT YOUR OWN RISKS, AND ONLY ON A MACHINE YOU ACCEPT TO CRASH AND REINSTALL. - BE AWARE THAT THIS DRIVER WILL GIVE FULL UNRESTRICTED (ROOT) ACCESS TO ALL YOUR EXT2FS PARTITIONS FROM OS/2. Now experience tends to prove that ext2-os2 is stable for normal use... but doing regular backups is never a bad practice. MAIN CHANGES SINCE PREVIOUS RELEASE : ------------------------------------- - bug fixes - performance improvements - removed the 2 Gb limit previously present in e2fsck, mke2fs and badblocks. INCLUDED IN THIS PACKAGE : -------------------------- The package includes Deon van der Westhuysen's Linux partition filter V 1.2c This filter driver will allow you to make you Linux partitions visible to OS/2 without altering the partition table, so that ext2-os2.ifs can mount them. This driver can also reorder hard drive letters assigned by OS/2 ; this can solve many partition headaches when having more than one operating system on a machine. Please look at the file ext2flt.doc and ext2-os2.inf for its usage and Deon's copyright notice. DEFAULTS SETTINGS : ------------------- - The default behavior after installation is read only. To turn on read/write access you have to specify -rw on the ext2-os2.ifs command line AND /W on the ext2flt.flt command line. - By default, ext2-os2 is case sensitive. It MUST be changed to case retensive if you plan to run programs from a Linux partition. See the online help file for details (-case_retensive option). FEATURES AND RESTRICTIONS OF THE 32 BITS VERSION OF EXT2-OS2 : -------------------------------------------------------------- OS/2 Requirements : - OS/2 WARP V4 : supported. - OS/2 WARP V3 : fixpack 17 or higher is required. Bare OS/2 WARP (no fixpack) should be OK but I did not test it. - OS/2 2.x : not supported. - OS/2 1.x : not supported. Benefits of the 32 bits version : - Now it can be compiled with a modern compiler (IBM Visualage C++) Old MS junks are no longer necessary (at least for ext2-os2.ifs) - Larger cache sizes can be used than with the 16 bits version. (system limits are a lot higher). - In some area, a significant performance gain can be observed (eg 25% on a 16 Mb file write). How does it work ? OS/2 still has a 16 bits Physical Device Driver model, as well as a 16 bits IFS model. An IFS is actually a library with a predefined set of entry points to perform file I/O operations. These entry points are 16 bits protect mode. The first thing each entry point does is to load 32 bits FLAT segment registers and jump to the 32 bits routine performing the actual operation. Before doing the actual job, 16 bits pointers passed to the routine are converted to 32 bits pointers using a kernel helper. This process is known as "thunking". In OS/2 kernel mode, this thunking is fast and efficient since stack switching is not required (the stack segment register is not reloaded). At some point, the IFS may need to call the kernel for some services. Here again, as the kernel services are 16 bits entry points (Device Helpers, File System Helpers), this thunking process is necessary. To do this I wrote an interface to Device Helpers callable from 32 bits Visualage C++ code. Since this interface is generic and independant from ext2-os2.ifs, I isolated it in a separate driver (mwdd32.sys) so that other clients than ext2-os2.ifs can use it. Installation notice : a new component (mwdd32.sys) is necessary to make ext2-os2.ifs work. Don't remove mwdd32.sys from CONFIG.SYS !! Developping other 32 bits IFS or device drivers : Other device drivers and IFS can profit from the facilities I had to implement to port ext2-os2 to 32 bits. The package includes the file 32drv170.zip, which contains mwdd32.sys sources, as well as skeletons of a 32 bits BASEDEV and a 32 bits IFS. WHERE TO FIND EXT2-OS2 : ------------------------ You can find the latest version of ext2-os2 at the ext2-os2 home page : http://www.geocities.com/SiliconValley/Bay/5313 You can also find it at the usual ftp sites (or in their incoming directory) : ftp://ftp-os2.nmsu.edu/pub/os2/system/drivers/filesys/ext2_240.zip ftp://sunsite.unc.edu/pub/Linux/system/Filesystems/ext2/ext2_240.zip ftp://ftp.leo.org/pub/comp/os/os2/drivers/ifs/ext2_240.zip ftp://ftp-os2.cdrom.com/pub/os2/diskutil/ext2_240.zip FEEDBACK AND SUPPORT : ---------------------- Please feel free to contact me for any question on ext2-os2. You are also encouraged to give me some feedback on how it works on your system and what new features you would like ... this helps me improve it ! Both success stories and disasters interest me. Matthieu WILLM willm@ibm.net