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Kernel Fallback in 11.23

 
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Pete Randall
Outstanding Contributor

Kernel Fallback in 11.23

If I want to revert to my previous kernel in 11iV2, is it sufficient to

mv /stand/backup/vmunix /stand/vmunix
cp /stand/vmunix /stand/current/vmunix
-and-
mv /stand/system.prev /stand/current/system

or is there something else I need to do?


Pete

Pete
6 REPLIES 6
Pete Randall
Outstanding Contributor

Re: Kernel Fallback in 11.23

Actually, the more I look at it, it looks like I should be moving the system and vmunix files from /stand/backup to /stand.

Is that true?


Pete

Pete
James R. Ferguson
Acclaimed Contributor

Re: Kernel Fallback in 11.23

Hi Pete:

This section of the WorkGroup guide has a good overview of kernel management in 11.23.

http://docs.hp.com/en/B2355-90950/ch03s11.html

Have a look at the section titled "Booting a Saved Configuration".

Regards!

...JRF...
Solution

Re: Kernel Fallback in 11.23

Pete,

You shouldn't really be touching any of the files by hand. Use the kconfig(1m) command to see what you have and how to revert to older kernels.

So in your case:

kconfig

should show you the saved configurations. Chances are you have one called backup

kconfig -v backup

Tells you when it was from

So before you go back to this config you might want to save your existing config

kconfig -s petes_config
kconfig -t petes_config "Petes config taken whilst learning how kconfig works"

Then restore the old config

kconfig -l backup

You might need to reboot for some changes to come into effect

There are some straightforward examples on the man page as well.

HTH

Duncan

I am an HPE Employee
Accept or Kudo
Johnson Punniyalingam
Honored Contributor

Re: Kernel Fallback in 11.23

Procedures for Kernel Parameter changes
====================================
# cd /stand
# cp system system.prev.<050112>
# cp vmunix vmunix.prev.<050112>

# cd /stand/build
# /usr/lbin/sysadm/system_prep -s /stand/build/system
# vi /stand/build/system (....edit the file to make the necessary changes --> e.g. "max_thread_proc 3072")
# /usr/sbin/mk_kernel -s /stand/build/system
# mv system /stand/system
# /usr/sbin/kmupdate

Kernel update request is scheduled.

Default kernel /stand/vmunix will be updated by
newly built kernel /stand/build/vmunix_test
at next system shutdown or startup time.
Problems are common to all, but attitude makes the difference
Pete Randall
Outstanding Contributor

Re: Kernel Fallback in 11.23

Working on an NFS problem I applied a bundle of patches and rebooted. One of my applications (SAS) stopped working, so I used kconfig to load the backup kernel, rebooted and tried SAS again - it worked.

So, to my way of thinking, I've got a running kernel that's out of sync with the source files used to build it, i.e. the NFS patches updated the source but I reverted back to the previous kernel. I can't imagine that this is a good state to be in!

So, I have questions. First, is there a better way to fall back. I hesitated to try to swremove the 8 patches involved, they were installed in a bundle by using the get-patches script from the ITRC patch site ( I didn't see a corresponding get-rid-of-patches script, by the way).

Second, when I look at the kernel configs I have now, it looks like the running kernel is the same as the one I was running prior to my "kconfig -l backup" command and subsequent reboot. How can that be?

# kconfig -v
Configuration NFSPatch
Title SAS fails after NFS/AutoFS patches
Save Time Thu Feb 19 06:36:35 2009
Modify Time Thu Feb 19 06:37:10 2009
Kernel Path /stand/NFSPatch/vmunix

Configuration backup
Title Automatic Backup
Save Time Tue Feb 17 12:14:35 2009
Modify Time Tue Feb 17 12:14:35 2009
Kernel Path /stand/backup/vmunix

Configuration last_install
Title Created by last OS install
Save Time Tue Jan 27 11:36:18 2009
Modify Time Tue Jan 27 11:36:18 2009
Kernel Path /stand/last_install/vmunix

# ll /stand/*/vmunix
-rwxr-xr-x 3 root sys 67322912 Feb 17 12:14 /stand/NFSPatch/vmuni
x
-rwxr-xr-x 2 root sys 67376600 Jan 29 14:06 /stand/backup/vmunix
-rwxr-xr-x 3 root sys 67322912 Feb 17 12:14 /stand/current/vmunix

-rwxr-xr-x 1 root sys 67374424 Jan 27 11:26 /stand/last_install/v
munix
-rwxr-xr-x 3 root sys 67322912 Feb 17 12:14 /stand/nextboot/vmuni
x

# ll /stand/vmunix
-rwxr-xr-x 3 root sys 67322912 Feb 17 12:14 /stand/vmunix


Pete

Pete
Pete Randall
Outstanding Contributor

Re: Kernel Fallback in 11.23

I forgot to mention that I did a "kconfig -s NFSPatch" prior to re-loading the backup kernel.


Pete

Pete