Hey Yosemite!

efibootmgr and x86_64-unknown-linux-gnu grub managed to get 16 boot penguins across the top of a 4k monitor with room to spare.  The secret is the "set gfxmode=3840x2160x32" configuration line in grub.cfg which deploys the kernel's efifb to set the boot resolution.  The default is 800x600x32 which explains why 16 penguins will not fit.  So far I've been only able to get 4k on bootup using grub.

If someone knows better I am all ears.

Life is good,
Maurice

... Wyrd bi¨ swi¨re, Meotud meahtigra, ¨onne ‘nges monnes gehygd.
    Fate is stronger, the Lord mightier, than any man's thoughts.
--- GNU bash, version 5.1.16(1)-release (x86_64-lilmikii-linux-gnu)