For several years I have run both the Knoppix ISO-image and disk-based versions under kvm for installs, maintenance etc. The basic method works for 8.3 too, but only as far as the first flash install.
Klaus K has made Knoppix more "fool-proof" to run under kvm by restricting it to read-only mode. For many users, that is clearly a feature: You may run your ordinary Knoppix install under kvm so it functions as both host and guest at once, but if persistent store is involved, and the host and the guest instances perform different updates to that, then what?
It is only a question of time until the file system is corrupted - it is easy to imagine that prof. Knopper has introduced this restriction from experiences with broken systems.
The bug is that it doesn't stop there. If you run different copies of Knoppix on different partitions, or run Knoppix under another OS variety, even another version of Knoppix, the only thing to be careful about is that the partition where the persistent store of the VM resides is not writable by other OS'es. But don't try to explain that to Knoppix 8.3. It only checks whether it is run under kvm, and in that case, the system is mounted read-only. Which kind of blocks many important uses of Knoppix images.
While the default behaviour is "correct", there must be a cheatcode for disabling it, e.g. VIRTWRITE. I guess specialists on minirt.gz should not have too much problems rolling their own, but this is a general issue, so for me it belongs in Knopper-land proper.
Vintage Computer, Memorex Storage Unit For Main Frame Computer 1986, Movie Prop
$995.00
IBM FRU26F7630 3390 DASD Hard Drive 10.8” from Vintage Mainframe
$249.99
Vintage Computer Punch Plug Board Mainframe Panels & Wiring Harness
$50.00
*PAIR* 1960's Vintage GE-600 Series Mainframe Computer PCBs Bitslice Accumulator
$14.95
Digital DEC LK201 Terminal Keyboard RJ11 Connection Mainframe
$49.00
Vintage Hewlett Packard HP 2100A Microprogrammable Computer System Mainframe
$999.99
AST Bravo MS P/60 Vintage Mainframe Computer Old IBM Style NO HDD
$129.95
Chrislin Industries CI-1123 PDP-11 Q-Bus DRAM Card, Untested
$100.00
JINX Gaming Computer Mainframe Rare Collectible
$500.00
AOC 14in Monochrome Monitor MM-413S VGA Mainframe Collection RARE 1993
$174.99