Hi, hlyg wrote: > in debian, it is as easy as copying iso file to usb device (/dev/sdx), run > sync to be safe > Does this method work for other iso file?
This depends on its content. The machine firmware looks for the existence of boot entry points. In case of x86: El Torito Catalog for optical media. Master Boot Record (MBR) and EFI System Partition (ESP) for USB stick. > http://ftp.funet.fi/pub/unix/FreeBSD/releases/ISO-IMAGES/13.1/FreeBSD-13.1-R ELEASE-i386-bootonly.iso > i can't boot it created this way. what's wrong with it? It only has El Torito but neither MBR nor ESP: $ xorriso -indev FreeBSD-13.1-RELEASE-i386-bootonly.iso -report_el_torito plain -report_system_area plain ... El Torito catalog : 19 1 El Torito images : N Pltf B Emul Ld_seg Hdpt Ldsiz LBA El Torito boot img : 1 BIOS y none 0x0000 0x00 4 20 El Torito img blks : 1 4 xorriso : NOTE : No System Area was loaded $ So it will boot only from optical medium and only by Legacy BIOS, not by EFI. (You may enable CSM in EFI, to get legacy behavior.) David Wright wrote: > It doesn't say you can do that with the i386 architecture, only amd64: > [...] > Additionally, this can be written to a USB memory stick (flash > drive) for the amd64 architecture and used to do an install on Indeed: $ wget http://ftp.funet.fi/pub/unix/FreeBSD/releases/ISO-IMAGES/13.1/FreeBSD-13.1-RELEASE-amd64-bootonly.iso ... $ xorriso -indev FreeBSD-13.1-RELEASE-amd64-bootonly.iso -report_el_torito plain -report_system_area plain ... El Torito catalog : 19 1 El Torito images : N Pltf B Emul Ld_seg Hdpt Ldsiz LBA El Torito boot img : 1 BIOS y none 0x0000 0x00 4 1044 El Torito boot img : 2 UEFI y none 0x0000 0x00 4096 20 ... System area summary: MBR protective-msdos-label cyl-align-off GPT ... MBR partition table: N Status Type Start Blocks MBR partition : 1 0x00 0xee 1 749759 ... GPT : N Info GPT backup problems: Not a GPT 1.0 header of 92 bytes for 128 bytes per entry GPT disk GUID : 82447345d3d1ec11b6df0cc47ad8b808 GPT entry array : 2 4 separated GPT lba range : 3 749757 749759 GPT partition name : 1 GPT partition GUID : 1 73447345d3d1ec11b6df0cc47ad8b808 GPT type GUID : 1 9d6bbd83417fdc11be0b001560b84f0f GPT partition flags: 1 0x0000000000000000 GPT start and size : 1 3 26 GPT partition name : 2 GPT partition GUID : 2 78447345d3d1ec11b6df0cc47ad8b808 GPT type GUID : 2 28732ac11ff8d211ba4b00a0c93ec93b GPT partition flags: 2 0x0000000000000000 GPT start and size : 2 80 4096 So here we have the full equipment for legacy BIOS and EFI. The MBR code is supposed to strat the boot procedure from USB stick on EFI. The MBR partition table indicates the presence of a GPT partition table. GPT partition 2 bears the type GUID of an EFI System partition. (Obviously there is no GPT backup table at the end of the ISO image. That's not compliant to GPT specs, but should not hamper booting.) Have a nice day :) Thomas
