How do you read an IRIX cd using EFS

[ablecode]

I am trying to read an IRIX cd that is in the EFS format using NetBSD 5.0.1

I added support for the EFS file system in the kernel and checked to see that pseudo-device vnd was in the conf file as well. I then built the kernel and installed it.

I issued the command

mount -t efs /dev/cd0a /cdrom

and it returned

Superblock read failed

I thought this might be because the cd uses 512 byte blocks so I used dd to make an image of the disk. I then tried

vnconfig vnd0 /temp/test.iso

which does not return an error. Then I did

mount -t efs /dev/vnd0a /mnt

and it returned

efs: invalid superblock: sb_magic invalid

Is there something I am missing, or is it impossible to read an IRIX cd in EFS format using NetBSD? If so, I finally have to switch to Linux.