Dual Processors in Red Hat 7.3

[JourdainJR]

I have a dual processor motherboard with RH installed.
Currently I have 1 processor installed. I just bought another one. Will it work right away in Linux or do I have to do something to get it to work???

[MaxWave]

yes, you will. As far as I know you will have to run a different kernel with SMP support.

I.E. 2.4.18-10smp versus 2.4.18-10.

Maybe you have to recompile kernel with SMP support. Not sure, really.

[doublec16]

You will have to recompile the kernel with SMP enabled if it isn't already. I believe that's all I had to do to get both CPUs to show up. You can install the second CPU to see if it works, and if it doesn't, try recompiling the kernel.

Edit: I found the Linux forum at 2cpu.com very helpful when I was getting my dual board running in Linux. They are very knowledgeable about specific issues and problems you may encounter when getting both processors to run in Linux, including the correct kernel to use. Yours is probably ok, but I did it a while ago and it turned out I had to upgrade the kernel to get it to recognise both CPUs. Also, you don't mention which board and CPUs you are using. If you encounter any problems, that would be a good thing to include in your post.

[Bokkenka]

If you only had one cpu running when you installed RedHat, it prob'ly didn't choose a SMP kernel. SMP is symmetric multi-processing.

I would try putting it in, and booting. The board will still run, even if only one cpu is recognized by the OS. Much like running Windows 95/98/ME/XP-Home. When you get it booted, log in and run the command "cat /proc/cpuinfo" either at the command line or a terminal window in X. If it reports a "processor 0" and a "processor 1", you should be good to go. If it only reports "processor 0", you'll need to get another kernel.

Mount your installation cd and look for the kernel with "smp" in it, and try installing it. "rpm -ivh kernel*smp*rpm" should do it. If you don't find one on your disks, you can go to ftp.redhat.com and drill down to the 7.3 RPMs and get it. There are three versions; athlon, 586 (pentium), or 686 (celeron and pentium2 or better). The rpm will install several files to the /boot directory, along with many in the /lib.

Then you will need to look into your /boot/grub/grub.conf file to see what's there. You should have something like this...# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You do not have a /boot partition. This means that
# all kernel and initrd paths are relative to /, eg.
# root (hd0,0)
# kernel /boot/vmlinuz-version ro root=/dev/sda1
# initrd /boot/initrd-version.img
#boot=/dev/sda
default=0
timeout=10
splashimage=(hd0,0)/boot/grub/splash.xpm.gz
title linux
root (hd0,0)
kernel /boot/vmlinuz ro root=/dev/sda1
initrd /boot/initrd.img
If you are dual booting, there will be a listing with "title windows" and whatever follows it. You need to add a listing to point to the new smp-kernel. Copy everything in the original "title linux" listing and paste it right below. Then, change the tile to "linux smp" or something. Then, change the kernel line to point to the new one, prob'ly "vmlinuz-2.4.##-#smp", replacing the #s with the correct numbers. I don't know if you need to change the initrd line. I don't think so.

[cyberhwk]

not to be a jerk but you bought the cpus at diffrent times?
R you sure they are a matched set?
There isn't much room for play on matched cpus as far as I know.