Hello, In my ubuntu 20.04 machine, ckim@ckim-ubuntu:~$ dmesg | grep 'Command' [ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-5.11.0-36-generic root=UUID=5252b177-1243-4d3f-8a1a-ec7d0dcae011 ro quiet splash vt.handoff=7 ckim@ckim-ubuntu:~$ mount | grep boot /dev/sda2 on /boot/efi type vfat (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortnam e=mixed,errors=remount-ro) The kernel image in /boot/ directory was used and the /boot directory is in /dev/sda2, a hard disk. I'm almost sure but is this possible because (my system used UEFI for booting, I can see /boot/efi/EFI/ directory) 1. the UEFI firmware has file system driver and could open the disk partition and used the kernel image to boot 2. the UEFI firmware detected the disk (using SCSI driver?) and edited the system hardware information (here maybe ACPI table) and passed it to linux kernel. Is my understanding correct? Thanks in advance. Regards, Chan Kim