In the current state it does not do anything useful,
just lets systemd spam in logs.

ttyS0 is needed qemu. ttySIF0 needs to be set separately.

UBOOT_NOFDTDIR does not need more, так как bootload in QEMU uses
U-Boot/EFI.

QEMU for riscv virt machine passes its own DTB. Overriding DTB breaks
Linux loading.

ttySI0 was a name of HiFive Unleashed serial console. It was changed to
ttySIF0.

It is possible to set a timeout for automatic bootloading via a
variable.

Booting to Raspberry Pi 4 is not possible with these parameter.

When loading u-boot + extlinux.conf, needs specific arguments that
are not needed when using grub-efi