Hi, Pascal Hambourg wrote: > I did not have trouble with the Apple partition table except when using > libparted-based partition editors, but could you explain how you remove it ?
By dd-ing the first 32 bytes from file "isohdpfx.bin" of package "isolinux" onto the first 32 bytes of the ISO image (as data file with conv=notrunc or as USB stick). debian-9.3.0-amd64-netinst.iso has in its MBR the APM signature and a fake block count which happen to be x86 machine code without undesirable side effects: 00000000 : 45 52 08 00 00 00 90 90 00 00 00 00 00 00 00 00 00000010 : 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 The first 432 bytes of amd64 and i386 isohybrid ISOs stem from /usr/lib/ISOLINUX/isohdpfx.bin which has x86 code that is similarly harmless but does not indicate APM: 00000000 : 33 ed 90 90 90 90 90 90 90 90 90 90 90 90 90 90 00000010 : 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 This jackalope was invented by Matthew J. Garrett. https://mjg59.dreamwidth.org/11285.html Of course one may use own useless x86 code to deface APM. Some machine code knowledge would be precondition, though. Assembler source of isohdpfx.bin is at https://github.com/geneC/syslinux/blob/master/mbr/isohdpfx.S > (Strangely enough, wipefs does not find the GPT) The GPT in mjg's layout is not valid, because the partition table of the MBR does not consist of a single partition of type 0xee which starts at LBA 1. I meanwhile doubt that it is of any use. The history of mjg's development indicates that he first started with valid GPT and then ihad to add a MBR partition of type 0xef for marking the EFI System Partition / Boot Image, because some machines did not work with the GPT marked EFI partition. Partition editors like gparted or gdisk detect the presence of the GPT header block at LBA 1 and then complain about the wrong MBR partition table. This can be silenced by zeroing bytes 512 to 1023 of the ISO. A valid GPT can be found in grub-mkrescue ISOs which were produced while GRUB binary packages for 32-bit EFI and/or 64-bit EFI were installed. Have a nice day :) Thomas
