i've never used memtest86.
make memtest86 the payload. be sure to build with serial console only.
no, no, that does not work. the payload is never loaded/reached. the trouble is caused earier! right after crt0.s a jmp to the copied mem is done. the copied mem is c_start.s at the beginning. there it seems to stop. (otherwise i'd see the messages from hardwaremain.c, am i wrong?)
anyway -- running memtest86 with lilo right now and it seems that everything is fine (test4 is running. it will take some time to finnish). i dont think it is a mem problem (but i might be wrong).
niki