Yo go as root:
1) modprobe nbd max_part=8
2) qemu-nbd --connect=/dev/nbd0 /root/arm-emul/hda.img
Then you mount it:
3) mount /dev/nbd0p1 /mnt/aqui
When done, unmount and unshare it:
4) umount /mnt/aqui 5) nbd-client -d /dev/nbd0
That is all. Cheers