I don't think it is very fruitful to discuss upper memory for 32-bits processors. In my first reply, I just wanted to point out that the "non-detection" is quite normal, and I would hardly call it an error that Knoppix is configured more restrictively than possible with the latest gen processors. And what really makes this a non-issue, is - I also pointed this out - if one needs to use all RAM, start in 64-bits mode. (To stuff a 32-bits machine with 4+ GB RAM seems rather meaningless to me, but it can of course be done, kind of retrocomputing bringing back memories of 16-bits computing and a total of 20 bits address space. 64G addressing (32+4 bits) on 32-bits is analogous, and to me hardly more attractive when you get a decent 64-bits computer for a few hundred dollars.
I'd like to get back to discussing booting. I personally think grub4dos may be the best way to go, legacy grub is too limited and grub2 has gone astray.
HP Desktop i5 OR I7 Computer Mini PC Up To 32GB RAM 2TB SSD Windows 10 Pro WiFi
$220.00
FAST Dell TOUCHSCREEN 8th Gen Intel i7-i5 4Core 16GB RAM Pick SSD Wi-Fi BT Win11
$195.00
Dell OptiPlex 3060 MICRO DESKTOP PC COMPUTER I5 8TH GEN UP TO 32GB UP TO 2TB M.2
$295.00
Dell 15.6" NVIDIA Gaming Laptop - Intel Quad Core i7 64GB RAM 2TB SSD Windows 11
$523.00
Intel - Core i5-13600K 13th Gen 14 cores 6 P-cores + 8 E-cores 24M Cache, 3.5...
$314.99
Intel - Core i7-13700K 13th Gen 16 cores 8 P-cores + 8 E-cores 30M Cache, 3.4...
$449.99
Dell Optiplex 3080 Micro 10th Gen i5 6Core/8Gb/256Gb Nvme SSD/Wifi/HDMI/Win11 A2
$249.00
Intel Xeon E5-2670 2.6GHz 8 Core 20MB Cache Socket 2011 CPU Processor SR0KX
$5.95
Dell Optiplex 5040 MT Core i5-6500 3.20GHZ 8GB RAM 256GB SSD Win 10 Pro WiFi
$89.99
Windows 11 Home Mini PC Intel N4100 Quad Core 2.7GHz 8GB RAM DDR4 256GB SSD
$79.99