On Mon, 21 Nov 2022 21:10:04 -0500
Felix Miata
\EFI\BOOT\GRUBX64.EFI on host gb250 ESP is 1,116,024 bytes and seems to be the original from when Ubuntu 18.04 was first added to the NVME's ESP /following/ Leap and TW installation, while /boot/efi/EFI/opensusetw/grubx64.efi is recent and 143,360 bytes, roughly 1/8 the size of buntu's in BOOT/. /boot/efi/EFI/debian12/grubx64.efi is more like 1/9 the size at 121,856 bytes, while /boot/efi/EFI/ubuntu22/grubx64.efi is a match for the one in BOOT/ @1,116,024 with same timestamp. https://download.opensuse.org/tumbleweed/repo/oss/EFI/BOOT/bootx64.efi is 934,024 bytes.
It has been a while since I last installed Ubuntu. So this might be out-of-date. For Ubuntu, the file "grubx64.efi" is the equivalent of the openSUSE "grub.efi". That is to say, it is the module called by shim (or "shimx64.efi" on Ubuntu). If you want the equivalent of the openSUSE "grubx64.efi" then you have to manually install grub with options to exclude secure-boot support. Again, this might be out-of-date information.
1-Are these grubx64.efi files created on installation specific to the installation, as was done in the MBR track on legacy partitioned disks, or simply extracted from an rpm?
On openSUSE, that file is specific to the installation and may encode information about disk file systems to use. For Ubuntu, that file is the same for all installs.
3-Why is the one in BOOT from Ubuntu an apparent match to that in the ubuntu22 directory, yet those from openSUSE on BOOT either a match to one in opensusetw, or vastly larger?
In an openSUSE install, the "BOOT" directory contains a "grub.efi" which matches the "grub.efi" in the "opensuse" directory
4-Is it a problem, or can it be, if none of grubx64.efi or bootx64.efi or BOOTX64.EFI in /boot/efi/EFI/BOOT/ match grubx64.efi in any other directory in /boot/efi/EFI/, particularly the one that has efibootmgr priority on a normal boot?
For Ubuntu, the "efibootmgr" entry should be for "shimx64.efi".