Very interesting, Thomas. I'm writing this e-mail from the Debian system I've installed using the method you described in detail. The only difference is that I used cp instead of dd. My USB stick has now 3 partitions, two of them reserved for images and the other one for regular use. I included a README in the stick that describes in a very general way the steps taken to make it work, for future reference in the case I need it. I will include it here, for it might be useful to someone else:
Preparing a USB stick to boot Debian: * > 1. lsblk to find out device number. > 2. Unmount device. > 3. Wipe filesystem signatures if there was an image written to the stick. > 4. Partition USB stick with parted (don't forget the boot flag). > 5. Create the filesystems. > 6. Download .iso. > 7. Copy .iso (to preserve the original one). > 8. isohybrid --partok copied .iso. > 9. As root, cp "partoked".iso /dev/sdXY && sync. > 10. Reboot and select the USB stick to boot. * Under BIOS at least Thank you very much for the replies! PS - I'm curious about this: when I opened the images with an archive manager (more specifically with the one that comes with the MATE desktop), I saw a directory named "[BOOT]" that contained files with a name along the lines of "...no-emulation...". The date of creation was 1969. Pretty weird, haha. Do you have any idea about what it is? On 4 May 2016 at 02:59, Thomas Schmitt <[email protected]> wrote: > Hi, > > > Does the method described in the manual (copying to /dev/sdX) work under > > UEFI? Or it's basically the same thing as copying to a partition? > > The main difference is that copying to /dev/sdX overwrites the MBR and > the partition tables, while copying to /dev/sdXn keeps the partitioning > (and the other partitions' content) unchanged. > > BIOS booting from MBR does not necessarily need a partition table. > (It's the parted MBR code which looks for a partition marked as bootable, > not the BIOS firmware which simply starts the MBR code as x86 program.) > > But UEFI wants to see a EFI System Partition announced by MBR or GPT. > By copying the Debian ISO image to a partition you do not create a new > EFI System Partition. By copying it to the base device, you give it > the partition tables which are stored in the ISO. > > So if you put the Debian ISO into a partition, then for UEFI you'd > need to extract the content of the EFI System Partition from the ISO > and put it into a separate MBR partition of type 0xef. > > Debian i386 and amd64 netinst ISOs have their EFI System Partition content > in file /boot/grub/efi.img . In general you can ask a partition editor > to print the table > > $ /sbin/fdisk -lu debian-8.2.0-i386-netinst.iso > ... > Device Boot Start End Sectors Size Id Type > debian-8.2.0-i386-netinst.iso1 * 0 645119 645120 315M 0 Empty > debian-8.2.0-i386-netinst.iso2 4020 4659 640 320K ef EFI > (FAT-12/16 > > and use dd to cut out the content of the partition with id "ef": > > dd if=debian-8.2.0-i386-netinst.iso bs=512 skip=4020 count=640 > of=my_esp.img > > > The next problem might be that the starting system software normally > expects to wake up on /dev/srY or /dev/sdX, not on /dev/sdX1. > That's the realm of the debian-cd project. My scope ends when the > boot loader has started. > (It is the most interesting part of your adventure that the system > boots from /dev/sdX1 via BIOS. There is some hope it will do for > UEFI, too.) > > > Have a nice day :) > > Thomas > > -- Renato Bispo
