SCO Unix - How do I boot the old kernel?

satguru used Ask the Experts™
My questions are about re-linking the kernel and rebuilding the kernel environment.
What does "rebuilding the kernel environment do"?
Is it required when re-linking the kernel?
How can I boot the old kernel if the new kernel fails, or has some wrong behavior?

I am afraid what will happen if the new kernel won't boot, or if there is erratic behavior with the new kernel.
How can I boot the previous kernel that was working fine?
Will the old kernel have trouble if I said "yes" to rebuild the kernel environment when creating the new kernel?

NOTE:  I see this when unix boots if I wait 60 seconds, or hit the enter key

OpenServer Release 5
hd(40)unix swap=hd(41) dump=hd(41) root=hd(42) auto

Sizing memory
....................  many rows of dots

I suspect that during the 60 second wait, I can type something to invoke the old kernel.
What do I type?
I have not found any documentation on this in man boot(HW)

Why am I doing this?
I have SCO OpenServer 5.0.7 Host Edition with Maintenance Pack 5
Host Edition does not include Networking.
Enterprise Edition is needed for networking.

I don't know why, but I have some network components on the server.
Perhaps they were installed by Maintenance Pack 5
inetd and ftpd are running every time the system starts.

I tried to add the Intel PRO 1000 LAN adapter with TCP/IP.
I was prompted to re-link the kernel.
I hedged.
I can't afford to end up with a system I can't boot.
I need to know if I can get back to the previous known-to-be-good kernel.

Satguru Khalsa
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Dr. KlahnPrincipal Software Engineer

How can I boot the previous kernel that was working fine?

Always make an image backup of the system drive before doing anything related to the kernel.  Then, no matter what happens, you can get back to the way things are without wondering "Did all those changes really back out?  What else might have changed that I don't know about?"


I spoke with a support person/consultant at Microlite.
He said I can ...

Make /stand temporarily write-able
make a backup copy of the current kernel
  cp -p /stand/unix /stand/unix.saved
Make /stand read-only
Then make the new kernel
Say "yes" to making the new kernel the default
shutdown and restart
At the boot: prompt, to get the previous kernel, just type

Alternatively, boot to single user mode
Make /stand temporarily write-able
rename or remove the new kernel
rename unix.saved to unix
Make /stand read-only
shutdown and restart
As noted in my last comment, I found a solution

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