[seL4] Only 512mb ram available on capdl-loader-image-arm-qemu-arm-virt image

Hi! I'm running a an aarch64 Linux guest with qemu with "qemu-system-aarch64 -machine virt,virtualization=on,highmem=off,secure=off -cpu cortex-a53 -m size=2048 (...) -kernel capdl-loader-image-arm-qemu-arm-virt". I have noticed that no matter how I set the "-m size" parameter that only 512MB are available to the Linux guest. Removing the "highmem=off" crashes the system. Ok, what is the fastest, easiest way to get a workaround to this (if possible)? and have much more RAM available to Linux guest? Best,