Hi, hans.ullr...@loop.de wrote: > The "Surface RT" is capable to start of an usb-stick, but it is EFI secured.
What exactly do you mean by "EFI secured" ? > However, the debian installer > (on intel hardware) can be started with uefi, too, so why should the same > not work with armhf? I just downloaded https://cdimage.debian.org/debian-cd/current/armhf/iso-cd/debian-10.1.0-armhf-netinst.iso It has an EFI system partition: $ /sbin/fdisk -l debian-10.1.0-armhf-netinst.iso ... Disklabel type: dos ... Device Boot Start End Sectors Size Id Type debian-10.1.0-armhf-netinst.iso1 0 948223 948224 463M 83 Linux debian-10.1.0-armhf-netinst.iso2 948224 950271 2048 1M ef EFI (FAT-12 $ expr 948224 '*' 512 485490688 $ mount -o offset=485490688 /dvdbuffer/debian-10.1.0-armhf-netinst.iso /mnt/fat $ find /mnt/fat /mnt/fat /mnt/fat/efi /mnt/fat/efi/boot /mnt/fat/efi/boot/bootarm.efi $ UEFI specs prescribe bootarm.efi as boot file name for "AArch32 architecture". It looks like a GRUB2 EFI boot program. $ strings /mnt/fat/efi/boot/bootarm.efi | less begins by "!This program cannot be run in DOS mode." and has lots of names beginning by "grub". Let's look at an amd64 ISO: $ /sbin/fdisk -l debian-10.0.0-amd64-netinst.iso ... Disklabel type: dos ... Device Boot Start End Sectors Size Id Type debian-10.0.0-amd64-netinst.iso1 * 0 684031 684032 334M 0 Empty debian-10.0.0-amd64-netinst.iso2 3808 9471 5664 2.8M ef EFI (FAT-12/ $ expr 3808 '*' 512 1949696 $ mount -o offset=1949696 debian-10.0.0-amd64-netinst.iso /mnt/fat $ find /mnt/fat /mnt/fat /mnt/fat/efi /mnt/fat/efi/boot /mnt/fat/efi/boot/bootx64.efi /mnt/fat/efi/boot/grubx64.efi /mnt/fat/efi/debian /mnt/fat/efi/debian/grub.cfg Afaik /efi/boot/bootx64.efi is the certified Secure Boot starter (shim): $ strings /mnt/fat/efi/boot/bootx64.efi | fgrep Microsoft | wc -w 145 The file grubx64.efi looks like GRUB2. So it could be about disabling Secure Boot. If this cannot be done, then you'd need to convince Debian to beg Microsoft for a signed shim for armhf and to then add armhf to https://wiki.debian.org/SecureBoot#Supported_architectures_and_packages Have a nice day :) Thomas