How to build iPXE VirtualBox ROM that fits into 56KB

make_vbox.sh

make_vbox() {
    pushd "$HOME/src/forked/ipxe/src" >/dev/null &&
    make CONFIG=vbox bin/intel--virtio-net--pcnet32.isarom && #EMBED=config/vbox/embedded.ipxe &&
    echo "Max size of VirtualBox ROM is 56KB, 57344 bytes" &&
    ls -l bin/intel--virtio-net--pcnet32.isarom &&
    prefix=$(date +%Y%m%d-%H%M%S) &&
    mkdir -p /ipxe/$prefix &&
    cp -v bin/intel--virtio-net--pcnet32.isarom /ipxe/$prefix/ &&
    echo -e "@echo off\r\nvboxmanage setextradata global VBoxInternal/Devices/pcbios/0/Config/LanBootRom C:\\Programs\\iPXE\\$prefix\\intel--virtio-net--pcnet32.isarom\r\nvboxmanage getextradata global enumerate\r\n" >/ipxe/setvboxrom.bat &&
    popd >/dev/null
}