I have an ageing but much loved Fedora Core 6 box for which I am attempting to compile a kernel more recent than 2.6.22, in order that I might employ its support for an eSATA card.
My Fedora box has a pair of 500G disks & uses LVM2 to pool most of their content into a large root file system. Together they form /dev/mapper/VolGroup00-LogVol00. All kernels reside in /boot which is on a more traditional /dev/sda1.
Once the newer kernel boots it very quickly cannot find /dev/mapper/VolGroup00-LogVol00 and panics, complaining that it cannot find /dev/root.
I have built my kernel using the config file '/boot/config-188.8.131.52-72.fc6' as inspiration, hoping that whichever arcane switch I needed would be set, but so far - in vain.
I am resisting the urge to upgrade something more recent, as that's quite a hammer to break a very small egg.
Your clues & boos are all most welcome,