funny NFS (Linux and Solaris)

[Jinsong Zhao <zhaojs@Cadence.COM>]

I exported one directory at my Linux to one Solaris 2.5.1 machine. On
Solaris, I ran 'ln -s /tmp tmp', then ran 'file tmp', it says:
"readlink error: Invalid argument". However, when I 'ls -l' on the
Linux, it is fine. 

Another problem is when I create a directory on Solaris and then want
to cd into it, it complains that it is not directory. When I check
that directory on Linux, everything is fine.

There must be some funny things going on between Solaris and Linux
over NFS. This kind of problem prevents me from building file system
around Linux.

The Solaris filesystem is using UFS, Linux is using ext2. 

Any suggestion?

Jinsong