Hi, bytes 512 to 768 of debian-10.0-sparc64-grub-NETINST-1.iso are all zero, except the numbers inserted by xorriso: At byte 552: 00 00 00 00 00 1a b0 0 At byte 560: 00 06 e9 f0 So something went wrong with boot block image production before the xorriso run, where it was used with -G. Have a nice day :) Thomas