After kernel upgrade of a CentOS 5.9 x64 NFS server, Apache web server on a Solaris 8 NFS client is unable to generate directory index for files on a NFS share. No problem if the NFS client is a CentOS 5.9 x86 client with kernel 2.6.18-348.3.1. Both NFS clients are using NFS3 protocol.
Downgrading the kernel of the NFS server from 2.6.18-348.4.1 to 2.6.18-308 have the problem fixed. It looks like the problem is related to the bug below,