Installing the para-virtualized drivers on a Red Hat Enterprise Linux 3 kernel prior to 2.4.21-52 may result in a warning message being displayed stating the modules have been compiled with a newer version than the running kernel.

This message, as seen below, can be safely ignored.

Warning: kernel-module version mismatch
                xen-platform-pci.o was compiled for kernel version 2.4.21-52.EL
                while this kernel is version 2.4.21-50.EL
                Warning: loading xen-platform-pci.o will taint the kernel: forced load
                See http://www.tux.org/lkml/#export-tainted for information about tainted modules
                Module xen-platform-pci loaded, with warnings

The important part of the message above is the last line which should state the module has been loaded with warnings.