Change kernel loaded from 2.6.9-55.ELlargesmp to 2.6.9-55.ELsmp
 

We are trying to load RHEL AS 4 Update 5 on a 4 CPU quad core HP DL580 G5 (7350 2.93Ghz).

It is loading the 2.6.9-55.ELlargesmp kernel which is not compatible with some multipathing drivers we want to load. These are compatible with the 2.6.9-55.ELsmp kernel which is not being compiled on installation.

How do we control the kernels that are compiled and loaded on installation?

Check and see if you have the kernel you want first;

rpm -qa 'kernel*'

If yes then simply as root using your choice of editor to make this the default kernel by editing the /boot/grub/grub.conf file, remember the counting starts at zero.

If not then install the kernel you want;

Using the installation media as the source: rpm -ivh kernel-2.6.9-55.ELsmp*.rpm --force
Using RHN: up2date --nox -f kernel-2.6.9-55.ELsmp

Then modify the /boot/grub.grub.conf file.

RHEL 4 2.6.9-55.ELsmp kernel max CPUs/cores
 

Lenard

Thanks for that. We have loaded and successfully forced the load of the ELsmp kernel, but this only shows 8 of the 16 cores present. One of my colleagues has since found a restriction that RHEL 4 U5 can only support 8 cores or CPUs with the ELsmp kernel.

(Taken from http://kbase.redhat.com/faq/FAQ_85_7936.shtm):
The largesmp kernel is required for any AMD64 or Intel EM64T host with more than 8 CPU cores (regardless of how many sockets).
On supported architectures, systems with greater than 8 cpus will get automatically installed with largesmp kernels.

Hence we have to use the 2.6.9-55.ELlargesmp kernel to get all 16 cores in RHEL 4 U5 or use RHEL 5 which has better support for quad core with the standard ELsmp kernel.

Thanks - problem closed