Unable to downgrade installed kernel on suse 11U4

The Rock
The Rock used Ask the Experts™
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Hello All,

I have suse 11u4 installed but having 3.0.101-107 kernel . But i need 3.0.101-63 as one module only works with "3.0.101-63".

this  "3.0.101-63" comes with default ISO from SLES but when i ma trying to install or upgrade in both situation in last it gives either dependency issue or rpm exec issue something. due to GLIBC.

I have only 2 opton to fix it:

1. Downgrade kernel from 107 to 63 (recommended)
2. Shifting or reload current module which is configured for "3.0.101-107" to "3.0.101-63" but dont know how.

Pease help
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David FavorLinux/LXD/WordPress/Hosting Savant
Distinguished Expert 2018

Commented:
This is correct behavior.

When you upgrade your Kernel, many other system libraries (like libc) can also update.

This, creates a cascade where all software dependent on libc also update.

Downgrading a Kernel really means downgrading... sometimes 100s of software packages.

Be very careful to only execute this type of action using a dryrun flag, till you get a clean downlevel.

If you somehow get some packages downleveled + other broken, you may end up with a Bricked system (unable to finish a clean boot).

If a client asked me to do this, I'd start with a fresh machine + install the exact kernel version, then port their code to the downlevel machine.

Using a fresh install of downleveled Kernels, is the cleanest/fastest way to produce your desired runtime environment + ensure you have a machine that boots.
Panagiotis ToumpaniarisSystem Architect

Commented:
You can install multiple kernel versions in suse :

https://www.suse.com/documentation/opensuse114/book_tuning/data/cha_tuning_multikernel_zypper.html

https://doc.opensuse.org/documentation/leap/reference/html/book.opensuse.reference/cha.tuning.multikernel.html

You can keep Older Kernels as Fallback.

Not sure how it will work after you have updated the kernel though.

Author

Commented:
Thanks for your suggestion but i need to install one more kernel which is lower then current one. not higher one.
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Author

Commented:
if kernel downgrade not possible then is it possible to use one custom module configured for diffrent kernel to with other kernel.
Panagiotis ToumpaniarisSystem Architect

Commented:
Modules are usually compiled using kernel headers of the same version as the kernel. In general it's incompatible with any other kernel version.

That been said, you can try to load it with
modprobe -f "module_name_here"

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which will ignore version checks.

Author

Commented:
ok this is the kernel i need to add with diffrent kernel:
host-192-168-1-118:/lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front # pwd
/lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front
host-192-168-1-118:/lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front # ls
scsi_ep_front.ko

I want to add this with :

host-192-168-1-118:/lib/modules/3.0.101-107-default/kernel/drivers # pwd
/lib/modules/3.0.101-107-default/kernel/drivers/

on same machine.
System Architect
Commented:
The command should be like:

modprob -f  /lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front/scsi_ep_front.ko

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but it is not certain it will work.
David FavorLinux/LXD/WordPress/Hosting Savant
Distinguished Expert 2018
Commented:
As Panagiotis said, likely this will fail.

This appears to be part of a SCSI disk subsystem. If this module in any way fits into the SCSI disk i/o, then a few things may occur...

If you the modprobe above works then...

1) All i/o may cease.

2) Your Kernel may simply crash.

3) If you're very unlucky, then disk i/o may continue with every disk write generating corrupt data.

If you do the modprobe above, be sure you only do this manually + that the scsi_ep_front.ko does not live in the normal modprobe directory of your Kernel. It shouldn't load, since it was built with a different Kernel. If it does for some reason look like an auto loadable module, you may have to put your machine in single user mode + remove this module, just to get a clean boot.

All in all, this mucking about with modules which mismatch your Kernel will likely end badly.

Author

Commented:
host-192-168-1-118:/lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front # ls -la
total 1492
drwxr-xr-x 2 root root    4096 Sep 27 12:03 .
drwxr-xr-x 3 root root    4096 Sep 27 12:03 ..
-rw-r--r-- 1 root root 1513353 Aug  3 10:38 scsi_ep_front.ko
host-192-168-1-118:/lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front # modprobe -f  /lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front/scsi_ep_front.ko
FATAL: Module /lib/modules/3.0.101_63_default/kernel/drivers/scsi/scsi_ep_front/scsi_ep_front.ko not found.
host-192-168-1-118:/lib/modules/3.0.101-63-default/kernel/drivers/scsi/scsi_ep_front #


Tried but this not work.

@David Favour - Agreed with you comments but sitiuation is diffcult - i need to make this module work without installing new machine. so either i should downgrade kernel to the needed one or manually add this module to the current kernel
Panagiotis ToumpaniarisSystem Architect

Commented:
This solution is best for inserting a module to the kernel, but it is not advisable in practice just as David said.

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