Loading iPXE from RPL

[man-x86]

I forgot to update this thread as I've made a little progress while trying to make this board booting.

The main goal was to have iPXE on very old motherboards, mostly for convenience over floppy disks and cdrom.
I noticed that I did most of the testing with an early 486 (HP Vectra 486M) and a 386 (Compaq Deskpro 386S).
Both of them did successfully load the ne2k_isa.pxe image, but it seems to fail to execute it.

I tried to modify the CFLAGS used for compiling iPXE (from no flags to -march=i386), without success.

Then I tried to put this ISA board in a PII motherboard. The system loads the ne2k_isa.pxe image, executes it, chainloads to iPXE and is able to (slowly) boot an OS.

Would iPXE be limited to 586 machines?
Has anyone actually tested it on 486/386 machines, except qemu?