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Old 10-25-2011, 05:29 PM   #1
Registered: Oct 2011
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Install older kernel module into newer kernel - no symbol version for module


Is a particular Linux kernel version backwards compatible with older
kernel modules?

I have build successfully a kernel module for two kernel versions
2.6.18 (CentOS 5.2) and 2.6.32 (CentOS6.0).

With kernel version 2.6.32 (CentOS6.0) running, I can successfully
insmod my 2.6.32 module into it. That's all well and good, life as
expected... However, with the same 2.6.32 kernel running, I cannot
seem to successfully insert into it my 2.6.18 (CentOS 5.2) built
module. When I try, I get the kernel error message: "no symbol version for module_layout".

Should I may able to (skipping the 'why would you do this' discussion... at least for the moment) take my kernel module built under 2.6.18 (CentOS 5.2) and insert it
successfully interl a running 2.6.32 (CentOS6.0) kernel?

Here's a little more info:

Centos6Machine# uname -r

Centos6Machine# modinfo mykernmod.ko
vermagic: 2.6.18-274.7.1.el5 SMP mod_unload 686 REGPARM 4KSTACKS

Old 10-25-2011, 06:02 PM   #2
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Originally Posted by bayoulinux View Post

Is a particular Linux kernel version backwards compatible with older
kernel modules?
No, it is only compatible with the kernel it was built for.
Old 10-25-2011, 10:25 PM   #3
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Absolutely not!!

When a module is loaded, it literally becomes a part of the kernel, as though it had been loaded at boot time.

If the module was not built precisely for the exact kernel image that it has just been made a blood-brother part of ... your system will explode.

Anytime you make any change whatsoever to "the kernel," you must rebuild the entire kernel, "modules and all."
Old 10-26-2011, 01:26 AM   #4
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The only way you can insert the module in the 2.6.32 kernel is by rebuilding the module from source.
Old 10-26-2011, 05:32 AM   #5
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Okay - its seem like "no" is the answer. ;-) I appreciate folks looking at the posting - thanks again.


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