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2. UMSDOS: Where is it ?

2.1 Copyright and License

This document is Copyright (c) 1995, Jacques Gelinas.

It may be distributed under the GNU Free Documentation License. You should have received a copy with it. If not, you can view it at

2.2 History

The Umsdos project was started in 1992 and made available to the net in January 1994 as a patch. It was included in the standard kernel distribution in July, starting with kernel 1.1.36.

Umsdos was early adopted in the Slackware distribution even before it was officially included in the official kernel.

Umsdos was improved starting at kernel 1.1.60. Its performance has been dramatically enhanced, especially for writing. Since 1.1.70 (around this), it is stable again.

A major bug was solve in Linux 1.2.2. This bug was causing some grief to users since the beginning (some file were silently renamed, giving the sad impression that they were deleted). Beware that Slackware 2.2 is still shipping release 1.2.1 of the kernel, so has this bug.

2.3 Availability

It is available as a patch for kernel 1.0.x. It is built-in for kernel 1.2. It can be compiled in or load as a module. Beware that for now, if you intend to load umsdos as a module, you must also use the Ms-DOS fs as a module. This come from a limitation in the module system (some symbols are only export when the drivers is installed as a module).

2.4 Distribution supporting it

So far, I think only Slackware does support it. I am surely wrong, so please send me info to correct this.

2.5 Home site

The home site for Umsdos is Look in the directory /pub/Linux/system/Filesystems/umsdos.

2.6 Technical documentation

There is quite a lot of documentation about the internal of Umsdos. It is available both in HTML and text format at the same location as the utilities.

As far as I know, the HTML version is not available online on any web site. You must down-load it and "UN-tar" it and read it locally.

2.7 Who wrote it

Jacques Gelinas

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