[dm-devel] device mapper error when attempting to install 2nd kernel on CentOS

[Michael Phoenix]

I am having trouble trying to install version 2.6.15 of the linux
kernel onto a machine that is currently running 2.6.9 version of the
kernel. I am using the 2.6.9 configuration file and running make
install successfully. When I try to boot the new kernel, I get the
following:
No entry for device mapper found Is device mapper driver missing from kernel?
Failure to communicate with kernel
mount: error 19 mounting ext3
mount: error 2 mounting none

Apparently the device mapper is being used on the current kernel and
does exist in the direcotory /sys/misc. What do I need to do to get my
new kernel to run? According to what I've read, every kernel since
2.6.9 should have it in the source.
I checked the .config file and couldn't find anything called device
mapper. There was an entry for an IOMAPPER associated with a certain
scsi device that was commented out, but I have no idea what to put
after =. I couldn't find a comparable entry using make menuconfig. Any
help would be greatly appreciated.
I don't really have any need for it so if I can get my kernel to run
without it that is an acceptable solution.

Mike