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.
Lenovo IdeaPad 5i Slim 5 16IRL8 16" (512GB SSD, Intel Core i5-1335U, 1.30GHz,...
$422.10
LENOVO P520 Workstation W-2135 up to 128GB RAM 4TB SSD Win11P WiFi DVD/RW Gaming
$439.88
Lenovo Workstation Gaming NVIDIA RTX 2080 W-2135 up to 128GB RAM 4TB SSD Win11P
$689.99
Notebook Lenovo Slim Pro 9 Laptop, 16" Glass, i9-13905H, GB, 1TB SSD
$1022.99
Lenovo IP 5 16IAU7 16" 2.5K Chromebook i3-1215U 8GB Ram 128GB eMMC Chrome OS
$219.99
Lenovo ThinkPad Yoga 11e 11.6" 2in1 Touch Intel Core i3 4GB RAM 128GB SSD Win10
$59.00
Lenovo ThinkPad X1 Nano 13" Touchscreen 2K i7-1180G7 16GB/256GB Win 10 Pro
$555.00
Lenovo Ideapad 1i 15.6" FHD Notebook Intel Core i5-1235U 8GB RAM 256GB SSD
$349.99
Lenovo K14 AMD Laptop, 14" FHD IPS LED , Ryzen 5 5600U, GB, 256GB SSD
$569.00
Lenovo ThinkPad 14" Laptop Computer Core i7 16GB RAM 256GB SSD Windows 10 Pro
$229.99