So based on that link, I applied below procedure 
-
duplicate folder /boot/efi/EFI/qubes into one named qubes2
cp -avr -- /boot/efi/EFI/qubes /boot/efi/EFI/qubes2 -
edit file xen.cfg in qubes2 folder to adapt options parameter dom0_mem=max:8192M and save
-
identify your boot partition disk with
df /boot/efiorlsblkcommand -
check the actual boot configuration with
efibootmgr -v -
add new boot and makes it first priority with command below to adapt to your hdd partition (-d and -p) and .efi correct path (-l) and desired name (-L)
efibootmgr -v -c -u -L Qubes2 -l /EFI/qubes2/xen.efi -d /dev/sda -p 1 -
reboot and check BIOS to make sure you boot on the correct one
It did boot correctly but when arriving at login it seems my usb doesn’t respond nor for mouse or keyboard or yubikey, at luks it did works tho.
How can I update xen configuration to apply RAM value of 8192M ?
Am I really the only one here who cares to have more RAM, or is the EFI thing that is not common ?
Why does standard Qubes OS installation doesn’t pick the max to fit the max available RAM ?
I know quite a lot of users who would have switch to qubesOS but the lack of RAM stopped them to do so, well if the standard install doesn’t even pick your hardware to fit it is surely a miss here…