Just wanted to share a solution to a problem I ran into recently that I didn't happen to find answers to from googling around, in case someone else runs into it.
Oracle recently released install media for Oracle Linux 5 Update 6. I found during some testing that when I installed 5.6 directly from the install media, the vmware-tools drivers would fail to load. However, if I installed from 5.5 media and installed the vmware-tools, then updated to 5.6, the drivers worked fine.
Turned out the problem was that apparently as of 5.6, Oracle made their own custom kernel - kernel-uek - the default boot kernel, and there's some incompatibility between the kernel and that vmware-tools build, or perhaps some other missing package dependency or library. When I switched to the non-uek kernel and rebooted, the vmware tools worked fine. The reason the 5.5->5.6 upgrade didn't cause a problem was it didn't make the uek kernel the default.
The vmware-tools packages I installed were pulled from http://packages.vmware.com/tools/esx/4.1/rhel5/x86_64/
After the fresh install of OL 5.6, this was the output of uname:
Linux localhost.localdomain 2.6.32-100.26.2.el5 #1 SMP Tue Jan 18 20:11:49 EST 2011 x86_64 x86_64 x86_64 GNU/Linux
And these were the kernel packages installed (both the "standard" kernel and the UEK kernel were installed, but the grub config had the uek kernel as the default):
kernel.x86_64 2.6.18-238.el5 installed
kernel-uek.x86_64 2.6.32-100.26.2.el5 installed
kernel-uek-firmware.noarch 2.6.32-100.26.2.el5 installed
This was just doing a completely default install from the 5.6 install media with no customization.
With the kernel-uek kernel loaded, the following messages were reported in dmesg output:
pvscsi: no symbol version for module_layout
vmxnet3: no symbol version for module_layout
vmci: no symbol version for module_layout
To fix the problem I just edited the /boot/grub/menu.lst and changed "default=0" to "default=1" and rebooted. We don't currently plan to use Oracle's kernel so that's a valid solution for us.
Most likely I'll be updating our kickstart config to just exclude the kernel-uek* packages but I haven't tested that yet. (I was just doing test builds from the install media to work on repackaging the vmxnet drivers into our kickstart boot iso.)