First of all, only 0, 4 and 5 are well-defined values for PXELINUX. 0x80 and -1 are applicable to ISOLINUX only. Out of those, 0 is the only value that matters in most contexts. At that point it's up to the BIOS, and if the BIOS doesn't handle it, then there is nothing I can do about it. Try using chain.c32. -hpa