$ binwalk moxa-edr-810-series-firmware-v5.1.rom

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
32            0x20            Linux kernel ARM boot executable zImage (little-endian)
13476         0x34A4          gzip compressed data, maximum compression, from Unix, last modified: 2019-03-14 01:36:42
4194336       0x400020        JFFS2 filesystem, little endian

$ qemu-img create rootfs.img 1G
$ mkfs.ext4 rootfs.img
$ sudo mount -o loop rootfs.img /mnt
$ sudo cp -r moxa_rootfs/ /mnt
$ sudo umount /mnt

$ qemu-system-arm -M versatilepb -nographic -kernel vmlinuz-3.2.0-4-versatile -hda rootfs.img -append "root=/dev/sda console=ttyS0"