DMSDOS - Linux kernel driver

DMSDOS is a loadable module for the Linux kernel. It provides read and write access to compressed FAT filesystems, such as Microsoft's Doublespace/ Drivespace and Stac's Stacker.

The original page maintained by Frank Gockel at the University of Duisburg.

DMSDOS capabilities

More about DMSDOS Capabilities and Restrictions

Dmsdos has been written by Frank Gockel and Pavel Pisa. The dmsdos html pages were originally an excerpt from the ascii text documentation and have been improved by Jaroslav Fojtik.
There's also a Japanese DMSDOS homepage maintained by Takafumi NAKA. 

The DMSDOS filesystem was thoroughly tested and a current version seems to be quite stable. But before using it you should be warned:

 Warning As there's no free documentation available about the inner workings of the CVFs (Compressed Volume Files) that the original software creates, dmsdos is the result from a lot of trial and error. What dmsdos does when reading and writing files may be awfully wrong according to the specification though it works in most cases.

There's no warranty. Use dmsdos completely at your own risk or don't use it at all. Make a full backup of your data before installing and using dmsdos to feel safe.

System requirements:

Currently it has been tested under Linux 2.0.29-36, and 2.1.80+ though 2.1.94 or newer is recommended. DMSDOS does not run with kernels 2.1.0 up to 2.1.79 and will never do so. It has also been reported to fail under 2.0.0 so just avoid too old kernels, please. The recommended kernel is 2.2.3 since all known FAT layer bugs that are triggered by dmsdos have been fixed in that kernel. For the 2.0 series, 2.0.36 is recommended, but please read the installation notes for necessary bugfix patches (the dmsdos package includes all the bugfix patches).

Related HTML pages:


mcdmsdos - utility to read DoubleSpace/Driverspace/Stacker compressed volumes as Midnight Commander virtual filesystem.

dmsdos- available (runs with late 2.0, late 2.1 and all 2.2 kernels) Since the amount of bug reports has significantly decreased up to now, that release is on its way to be called dmsdos 1.0 some day :))

Note that for kernels 2.2.13 and 2.2 14 a bugfix patch is needed (see the README file on the ftp server). This patch is not included in the dmsdos package yet so you must download it seperately :)

*** Kernel 2.3.xx/2.4 support (experimental) ***

dmsdos- does not run under latest 2.3.xx and probably 2.4 kernels because the Linux filesystem interface has again been redesigned.

The CVF-FAT interface is currently under rewrite for kernel 2.3.99. I hope to release dmsdos with support for the new kernels soon. A pre-release is under test (see here: Get the Source Code).
If you want to work with the test release, please disable writable mmap (you can find it under dmsdos expert configuration -> misc options). Note that using the new code is currently dangerous - it's a test release, I already said this :) Avoid mmapping files (it crashes). Avoid using high memory configuration in kernel (it crashes with this dmsdos release). But if you know how to make things work better, please let me know, of course :))

README file on the ftp server