use shmfs

[Hua Zhong]

Hi:

Currently I'm using shmfs as a volatile storage. I am using Monta Vista's
kernel (2.4.2). I added the following line in /etc/fstab:

tmpfs                   /dev/shm                shm     defaults        0 0

# df /dev/shm
Filesystem           1k-blocks      Used Available Use% Mounted on
tmpfs                        0         0         0   -  /dev/shm

the "0" number of blocks seems fishy.

I cannot write to the filesystem. write returns EINVAL. I can create an
empty file, however.

What should I do to make it work? Thanks.

By the way, I know tmpfs is a replacement of shmfs, but it's not in the
2.4.2 kernel I am using (can't find in config). Is it in any newer kernels
(especially 2.4.9)? Is it stable enough?

Thanks