Hi, Florian Pelz wrote: > my Macbook still does not like it.
The content of the EFI partition of guixsd-install-0.15.0.i686-linux.iso does not look like it is ready for 64-bit x86: $ mount guixsd-install-0.15.0.i686-linux.iso /mnt/iso $ mount /mnt/iso/efi.img /mnt/fat $ find /mnt/fat -exec ls -ld '{}' ';' drwxr-xr-x 3 root root 7680 Jan 1 1970 /mnt/fat drwxr-xr-x 3 root root 1024 Jul 6 2018 /mnt/fat/efi drwxr-xr-x 2 root root 1024 Jul 6 2018 /mnt/fat/efi/boot -rwxr-xr-x 1 root root 96256 Jul 6 2018 /mnt/fat/efi/boot/boot.efi -rwxr-xr-x 1 root root 96256 Jul 6 2018 /mnt/fat/efi/boot/bootia32.efi According to UEFI specs, bootia32.efi is the start program for 32-bit x86 systems. The name for 64-bit x86 systems would be bootx64.efi like in the EFI partition of debian-9.3.0-amd64-netinst.iso : drwxr-xr-x 3 root root 16384 Jan 1 1970 /mnt/fat drwxr-xr-x 3 root root 2048 Dec 9 2017 /mnt/fat/efi drwxr-xr-x 2 root root 2048 Dec 9 2017 /mnt/fat/efi/boot -rwxr-xr-x 1 root root 390656 Dec 9 2017 /mnt/fat/efi/boot/bootx64.efi (Afaik, the EFI partition image is created by grub-mkimage. But i may be wrong. Better check source of debian-cd or ask Steve McIntyre.) Was GRUB configured to produce 64-bit x86 code ? I only know how to do it with Debian. There i have to install the packages "grub-pc" for BIOS, "grub-efi-ia32-bin" for 32 bit x86 EFI, "grub-efi-amd64-bin" for 64 bit x86 EFI. The EFI partition then has: drwxr-xr-x 3 root root 7680 Jan 1 1970 /mnt/fat drwxr-xr-x 3 root root 1024 Feb 6 2016 /mnt/fat/efi drwxr-xr-x 2 root root 1024 Feb 6 2016 /mnt/fat/efi/boot -rwxr-xr-x 1 root root 132608 Feb 6 2016 /mnt/fat/efi/boot/bootx64.efi -rwxr-xr-x 1 root root 95744 Feb 6 2016 /mnt/fat/efi/boot/bootia32.efi -rwxr-xr-x 1 root root 95744 Feb 6 2016 /mnt/fat/efi/boot/boot.efi -rwxr-xr-x 1 root root 1759 Dec 10 2017 /mnt/fat/NvVars ("grub-pc" caused bootable MBR x85 code.) Have a nice day :) Thomas