[Yaffs] New dumb error: can't mount

I thought I'd try yaffs2ram file system on a suse 9.2 distro runing the
2.6.8 kernel. I installed the source in linux/fs and modified
linux/fs/Kconfig and linux/fs/Makefile appropriately.

My new kernel definitely knows about yaffs:

# cat /proc/yaffs
YAFFS built:Jun 3 2005 00:31:47
$Id: yaffs_fs.c,v 1.5 2005/04/29 07:01:18 charles Exp $
$Id: yaffs_guts.c,v 1.6 2005/04/24 09:57:06 charles Exp $

And I definitely have yaffs2ram support in my kernel config file:

CONFIG_YAFFS2_FS=y
CONFIG_YAFFS_YAFFS2=y
CONFIG_YAFFS2_MTD_ENABLED=y
CONFIG_YAFFS2_RAM_ENABLED=y
CONFIG_YAFFS2_USE_NANDECC=y
# CONFIG_YAFFS2_ECC_WRONG_ORDER is not set
CONFIG_YAFFS2_USE_GENERIC_RW=y
# CONFIG_YAFFS2_USE_HEADER_FILE_SIZE is not set
CONFIG_YAFFS2_DISABLE_CHUNK_ERASED_CHECK=y
CONFIG_YAFFS2_SHORT_NAMES_IN_RAM=y

But when I try to mount a yaffs2ram file system, I get an error:

# mount -v -t yaffs2ram yaffs2 /mnt/yaffs2ram
mount: special device yaffs2 does not exist

# uname -a
Linux marty 2.6.8-24-marty-yaffs2 #4 Fri Jun 3 00:51:33 PDT 2005 i686
i686 i386 GNU/Linux

# ls -ld /mnt/yaffs2ram
drwxr-xr-x 2 root root 4096 2005-06-02 09:56 /mnt/yaffs2ram

So I'm off to debug this, but any pointers as to what to look for would
be greatly appreciated.

Marty