I tried to install a root-encypted Debian 11 (Bullseye, netinst, daily build 2021-03-29, cryptsetup) next to the existing Win 10 as Dual boot on a strict UEFI-only system (Dell Inspiron 17 7706, BIOS 1.3.0, 16GB RAM, 512 GB NVMe).
Eventually I could shrink the Win10-partition, UEFI-boot the Netinst-Image, connect the Wifi (AX201) and install the encrypted Linux system, but grub-install
and efibootmgr
fail with
"EFI variables are not supported on this system"
modprobe efivars
resp. modprobe efivarsfs
fail either with
"modprobe: FATAL: Module efivarsfs not found in directory /lib/modules/5.10.0-5-amd64/"
Copying efivarsfs.ko there would make modprobe to work, but not grub-install/efibootmgr, leaving the system unbootable with Debian Linux (Win 10 boots).
I tried all the hints from "EFI variables are not supported on this system" but no success. Also tried the solutions from https://wiki.debian.org/GrubEFIReinstall no success either. Also tried rEFInd but it would not see my unenrypted boot-Partition at all.
/sys/firmware/efi/efivarsfs/ exists, but is empty. Secure boot is off.
Any ideas left?
Next step would be to try a plain new install of Ubuntu 20.10, but I'd like to stay with debian.
Thanks in advance for any help.