I have an ACER ASPIRE 5.14 laptop with an internal hard disk, with both Windows 10, & Ubuntu v.20.04 on separate partitions (which I use only occasionally), but have been running the machine primarily from a USB stick with Debian 11.6:
Linux cpe-67-241-65-193 5.10.0-21-amd64 #1 SMP Debian 5.10.162-1 (2023-01-21) x86_64 GNU/Linux The problem: > I can boot with Debian with no problems; > I can boot with Windows with no problems; > Through about May of 2022 I was able to also boot with Ubuntu, with no problems... but some time in the last half of 2022, I updated Debian, & now, although the Ubuntu option exists in the GRUB boot loader menu, when I select it, I get the error message: 'bad shim signature' & I cannot boot with Ubuntu any more. > To boot with Ubuntu, I have to disable secure boot in the BIOS/UEFI setup (F2 on my computer). With earlier versions of the kernel, I think one had to disable secure boot to boot with debian, but after kernel 5.10, one could boot with secure boot enabled, as my experiences through the middle of 2022 showed. > The APPARENT reason is that on the Debian boot volume, the /boot/efi/ directory contains: /EFI/debian/ fbx64.efi, grubx64.efi, mmx64.efi, shimx64.efi BOOTX64.CSV & grub.cfg I think the relevant file is the shimx64.efi file. On the Ubuntu volume, the /boot/efi/ directory is completely empty & I've not been able to find any files with names containing shim. My QUESTION: can I simply copy the /EFI/debian/... directory & files to the UBUNTU volume to enable the machine to boot when secure boot is enabled? My worry is that the Ubuntu OS uses a different version of kernel: the 2 most recent versions of kernel on each volume are: DEBIAN 11.6 | UBUNTU 5.10.0-20-amd64 | 5.15.0-67-generic 5.10.0-21-amd64 | 5.19.0-35-generic so the shimx64.efi may work for the debian OS but not the UBUNTU, though this shim 'boot-loader' is 'used' before the kernel, I think. I would be most appreciative of any advice, or suggestions for a better place to submit this question, if this forum's not appropriate. With many thanks, Ken (I have not subscribed to the list, but will try to check it; I would be very grateful if replies could be cc to my e-mail address: kcbl2...@yahoo.co.uk.)
