old-www/LDP/LG/issue01to08/ext2-os2_mar96.html

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<HEAD> <TITLE>Introduction to Ext-OS/2</TITLE> </HEAD>
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<P> <P> <H1>Read-Write Access to Linux Partitions Under OS/2</H1>
<P> by <B>Larry Ayers</B> <A HREF="mailto:
layers@vax2.rain.gen.mo.us">&lt;layers@vax2.rain.gen.mo.us&gt;</A><BR>
Copyright (c) 1996<BR> <H5>Published in Issue of the Linux Gazette</H5> <HR>
<CENTER><H2>Introduction</H2></CENTER>
Matthieu Willm, a German IBM employee, has been
creating (in his spare time) an ext2 filesystem driver for OS/2. It has been
through several beta levels now and seems stable and usable. Of course it
would be wise to have your backups all up-to-date before installing a package
which modifies the way your OS interprets the disk partition table!
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<CENTER><H3>Contents</H3></CENTER>
<P>The ext-os2 software is distributed as a zipped archive which contains
ample documentation, both in HTML format and in IBM's .inf format.
<P>An integral part of the package is a partition filter written by
Deon van der Westhuysen. This filter is loaded at bootup (via a config.sys
entry) and lets OS/2 assign drive letters to ext2 partitions. A switch can
follow the config.sys entry which will enable read-write access; the default
is read-only.
<P>Willm's filesystem driver is also loaded at boot-up. It's a strange
sensation to start up a filemanager under OS/2 and see several new
drive-letters included. Each Linux type 83 partition is assigned a
drive-letter beyond your present OS/2 and DOS partitions.
<P>As an example, my system's main linux partition becomes H:, and /usr/X11R6
becomes G:, and is not accessible from H:/X11R6. Symbolic links and
directory
mountings are ignored.
<CENTER><H3>Installation</H3></CENTER>
<P>The docs say you can install the package using the "Device Driver Install"
program, but for some reason this hasn't worked for me. The alternate manual
installation method, which consists of editing the config.sys file, worked
well, though.
<P>Since I don't always need to access Linux partitions, I did my config.sys
modifications to a copy named "config.l", in the \os2\boot directory, and
added a line (L: Linux access) to the altf1.bot file in the same directory.
This presents me with the choice of booting either with ext2 enabled or with
it disabled.
<P>
<CENTER><H3>The Monitor Utility</H3></CENTER>
<P>A PM notebook-style program is included which allows you to see how large
the dynamic cache has become, as well as a view of messages from the ifs
itself.<P>Click on these links to see screen shots of the monitor.<P>
<A HREF="./gx/ayers/ext2_1.gif">Page One: Ext-OS/2 Monitor</A><BR>
<A HREF="./gx/ayers/ext2_2.gif">Page Two: Ext-OS/2 Monitor</A><BR>
<A HREF="./gx/ayers/ext2_3.gif">Page Three: Ext-OS/2 Monitor</A><BR>
<P>
<CENTER><H3>Caveats</H3></CENTER>
<P>Installation of Ext-OS/2 does increase OS/2's memory usage, depending on
how much memory you allocate in config.sys for the dynamic cache (the default
and minimum is 245 kb.). All in all you can expect about a 300-400 kb.
memory
hit. A small, invisible program called ext_lw.exe is started from the
config.sys; its purpose is to continually attempt to shrink the amount of
memory used for dynamic cache. Its efforts are visible in the monitor
notebook.
<P>One thing to watch for, say if you should have an irrestible urge to edit
your .fvwmrc file while in an OS/2 session, is that your file will be saved
with the extra carriage-return (^M) at the end of every line, and your file
probably won't work! Either use one of those ubiquitous dos-to-unix
utilities
on the file after editing it, or use an OS/2 editor that knows how to write a
unix text file (like FTE).
<P>By default, every time you boot back to Linux a filesystem check is
forced,
which increases boot time by a few seconds. This can be disabled, but I
wouldn't recommend it.
<P>Remember to back everything up first! This program has worked remarkably
well for me, but YMMV!<P>
<CENTER><H3>Where To Get It</H3></CENTER>
<P>The current (as of 28 Jan 1996) Ext-OS/2 package is available via ftp
from:
<P>
<A HREF="ftp://hobbes.nmsu.edu/os2/new/ext2_07b.zip">hobbes.nmsu.edu </A>
<P>
<A HREF="ftp://ftp.cc.gatech.edu/pub/linux/Incoming/ext2_07b.zip">
ftp.cc.gatech.edu </A>
<P>
<A HREF="ftp://ftp.leo.org/pub/comp/os/os2/drivers/ifs/ext_07b.zip">
ftp.leo.org</A>
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