Hacking modversions

[Kyrre Ness Sjobak]

tir, 01.03.2005 kl. 19.43 skrev Mike Hearn:
> Hello,
> 
> I'd like to propose that kernel updates release via fedora-updates use the
> same modversions.h as the last one if there were no interface
> changes. I know that may be a controversial proposal, but read on.
> 
> For security fixes, it's rare (but not impossible) that a kernel interface
> changes. In this case it would be possible to use the same symbol mangling
> and therefore not prevent user-compiled modules from loading, and it would
> be safe. 
> 
> For the other updates released, more care would have to be taken
> to notice if there were changes or not - if there was any doubt about
> binary compatibility, then modversions would still change, but if there
> was simply eg, a driver bugfix then it would not be changed.
> 
> This solves the following problem:
> 
> Bill sets up a Linux system for Sally. She does a "yum upgrade" because
> she knows it's important to stay up to date to be secure. The kernel is
> changed, and as a result various things break even though the update was
> fixing a race condition in a syscall implementation. She does not
> know how to fix it. 
> 
> This is not a "please can the kernel have a stable ABI" email. 
> 
> It doesn't, and that's the end of the story. This is a "please do not
> prevent self-compiled modules from loading unless there is a real need"
> email, which I haven't seen brought up before (you have my apologies if it
> was) and should not have much impact outside a bit more work for Dave
> Jones I guess ;)
> 
> Is this possible to do? It would require a careful analysis of the changes
> being made to the kernel in online updates, but hopefully this already
> happens anyway :) The actual build system modifications should not be too
> tricky, I hope ...
> 
> thanks -mike

It *could* be great - exept, it trashes expectations (not correct word,
i know...). A user can today know "if i update my kernel i must *always*
recompile external modules". If this happens, it is "if i install a new
kernel, i *might* have to recompile my module, and only way (wihout
being a kernel guru) to know is to reboot and see what happens...".

Kyrre