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.
HPE BL460c G9 ProLiant Blade | 2x Xeon E5-2620V3 | NO RAM | P244BR | 2xHDD Tray
$179.00
HPE BL460c G9 ProLiant Blade | 2x Xeon E5-2630V3 | 32GB | P244BR | 2x300GB 15K
$299.00
HP ProLiant BL460c G9 (Gen9) 2x E5-2670V3 12 Core 3.1GHz No Ram or No Drives
$59.98
DELL PEM640 POWEREDGE M640 BLADE SERVER
$539.95
Dell PowerEdge M620 0F9HJC Blade Server 2*E5-2670 2.60GHz 192GB RAM 2*300GB SAS
$103.99
Dell M630 PowerEdge Blade Server
$700.00
DELL M630 BLADE SERVER x2 XEON E5-2660V3 @ 2.6GH H730 PERC HDD CADDIES 16GB FC
$50.00
Dell PowerEdge M630 Blade Server 1x Xeon E5-2630 v4 CPU / Motherboard P/N 0R10KG
$69.99
Dell PowerEdge M620 Blade Server
$39.99
Cisco UCS 5108 Blade Server Chassis Enclosure N20-C6508 4x PSU 8x Fans 2x Fabric
$139.99