Hi Hongyi, > I noticed that for many distro's install iso, there are some efi files > in the EFI/efi folder as follows: > bootx64.efi, loader.efi and grubx64.efi > > Say, for arch: > bootx64.efi, loader.efi > > for debian: > bootx64.efi grubx64.efi bootx64.efi is the default, others may exist as you can see. NVRAM defines a list to iterate over of *.efi to attempt. https://wiki.mageia.org/en/About_EFI_UEFI#The_ESP has some detail. The start of https://jdebp.eu/FGA/efi-boot-process.html may also be useful. -- Cheers, Ralph.