Creation of OS image for Realm and possible alternatives

[atulfj]

Hi,

In the following portion of launch-realm.sh:

./lkvm run \
	--debug \
	--realm \
	--measurement-algo="sha256" \
	--disable-sve \
	--console serial \
	--irqchip=gicv3 \
	--network mode=user \
	-m 256M \
	-c 1 \
	-k linux.realm \
	-i rootfs-realm.cpio.gz \
	-p "earlycon=ttyS0 printk.devkmsg=on" \
	--9p /shared,FMR

Islet currently uses linux.realm as its OS image. Is it a generic linux image, or has it been modified by Arm or Islet developers to support Realms? If yes, is there a source or documentation for the modifications? If not, could you suggest some alternative images that could be used instead? Thanks.