Only in education. Does anybody know if there is a way to fix this problem, short of starting over from scratch? While doing a kernel upgrade today, one of my students loaded the wrong kernel. There are 7 machines in the lab that use 586 kernel and 2 that need 686. Yes you guessed it, these rocket scientists loaded the Red Hat 2.4.18-19 update 586 version on a 686 machine. The machine still runs but has problems. Any help would be appreciated. I did try to install the proper kernel instead of upgrading, that didnt work.

You don't provide information as to the distrubition and/or how the kernel was installed/upgraded. I'm going to assume RedHat of some version with vendor-provided kernel RPMs.

You should not do a kernel "upgrade" via RPM. Always do an install, boot on the new, if all is well you can then de-install the RPM of the older version. If you did that, just choose the previous kernel from the LILO or GRUB boot menu. If that's not what was done and you only have 1 kernel to choose from and it's the one that is _working_ but incorrect, go ahead and install the new one now. Do it "rpm -ivh kernel.i686..." though.. If you're using grub then edit /etc/grub.conf to set that kernel as default OR just choose it when you reboot off the boot menu. Same for lilo but remember to run /sbin/lilo after making any changes to /etc/lilo.conf

RedHat .i386 .i586 and .i686 kernels are just compiles with optimizations for those particular processor classes. A .i386 one will run on just about any Intel CPU from 386 forward but perhaps not take advantage of new capabilities and therefore not run as fast or as efficient as it could have. Running a .586 optimized one on a newer CPU I would think would work fine... Probably best to install the .i686 one in your scenario though.

Good luck!