I have two servers running RHEL 5.4 quite happily. However, through simple oversight, AHCI/hotswap support was not enabled in BIOS at install time and is now needed. The machines are running ICH10R SATA controllers and kernel-xen-2.6.18-164.el5.
I tried restarting with AHCI enabled, but quite predictably, the machine refused to boot. There doesn't seem to be much online in the way of instructions for doing this in Linux, although there is a plethora of information on enabling AHCI post-install on Windows. I take it grub is the component choking, presumably because the change in driver messes with its device mappings?
What is the best way to go about enabling AHCI on an already running Linux installation?