[Teknoman117]

Just a few days ago I was trying to cut down the configuration for the current Linux kernel so I could boot it on a circa 2001 PC/104 SBC with 32 MiB of SDRAM. The processor is an AMD Elan SC520, which is a 133 MHz AM5x86 core and about on par with a 75 MHz Pentium. Sadly the memory is not expandable.

Getting a buildroot based system to work was fairly easy starting with "make tinyconfig" for the kernel. IDE was a real hangup because there really isn't an IDE controller, it's a legacy IDE interface with no DMA. Disk IO is abysmally slow. Found that libata has experimental support for legacy IDE, rather than use the old IDE drivers. So I've managed to not select any deprecated kernel options.

Booting a current Gentoo stage3 with networking was a major challenge though. Still haven't managed to get IPv6 and all of the standard netfilter modules before the kernel hangs mysteriously between finishing self extract and producing any logs.

I also haven't managed to get ZONE_DMA support working for legacy DMA on ISA (for the PC/104 bus) without it using too much of the remaining DMA'able memory to load the Intel 82559 ethernet driver (e100.ko).

It's rather hilarious seeing a 5.10 Linux kernel complaining that it can't find a 256 KiB contiguous region of physical ram.

Buildroot boots in a matter of seconds on it, Gentoo takes a few minutes.

[anthk]

Try Minix3 or NetBSD.