Re: [CI] Support for old kernels

[Brian J. W. <Bri...@co...>]

Marc-Christian Petersen wrote:
> 
> Hi Brian,
> 
> >We would like to get some feedback on which kernel versions we should
> >release CI patches against. Right now we have patches for vanilla
> >2.4.2 and 2.4.4. Very soon, we're planning to release CI 0.5.6, which
> >will support Alpha (in addition to x86) and include some bug fixes.
> I think a patch for the 2.2.19 Kernel could be very interesting, cause
> so
> many ppl (including me) are using 2.2.19 cause that was the real last
> stable
> kernel. And if you would do some actual patches for the 2.4 Kernel, i
> think
> it should be for 2.4.9-ac10 or later.


We don't have the resources to back-port our stuff to the 2.2 series. It
would be a non-trivial task for SSI, considering the number of hooks we
have in the base that would need to be reevaluated. There might also be
serious deadlock problems due to the lack of fine-grain locking in 2.2.
As it is, we've had to be a bit creative in 2.4. It's best to keep SSI
moving forward in kernel versions.

For CI, it might be a bit easier. CLMS (the membership subsystem) is
self-contained, without dependencies on the base. ICS (internode
communication) is already divided into transport dependent and
independent code. The transport dependent routines follow the ics_ll*
naming convention. They make use of the base TCP structures and
functions, and would need to be modified accordingly. There are also a
few hooks in the TCP code itself that would need to be adapted. We have
no plans to do this backport, but I don't think it would be terribly
difficult for someone else to do.

What's the advantage of being on Alan's kernel versus Linus'?


> 
> >For that release, we would like to bring the patch up to 2.4.6 and
> >just release for that kernel version. Are there any objections?
> The only objection i have is that the kernel 2.4.6 is very old and was
> not so
> stable as 2.4.4. Some of my friends and me had many troubles with the
> 2.4.6
> Kernel.
> 

I know. I think we moved up to 2.4.6 before it was out for very long,
then we got caught up in cranking out the SSI release, and preparing for
and doing a demo at Caldera Forum and LinuxWorld. We're now preparing
another SSI release with some fixes for bugs and memory leaks, and we
think we'll merge it up to 2.4.9 or 2.4.10. CI, being a subset of SSI,
should also merge up. I'll send a separate, shorter message to these
lists asking for opinions about this.


> >Once 2.4 has stabilized and been handed off to Alan Cox, it may make
> sense
> >to support more than one kernel version. At that point, people might be
> 
> >using old kernels because other patches they need haven't been updated
> in
> >awhile. Until then, however, I'm guessing that anybody who knows how to
> 
> >build a kernel wouldn't mind being on one of the latest and (hopefully)
> 
> >least buggy bases. Please let us know what you think.
> I think, 2.4.7 or 2.4.4 are more stable than 2.4.6, even the 2.4.9acX is
> very
> stable and therefore i think a newer CI Patch for a newer kernel would
> be
> very nice. I agree, 2.4 has not been fully stableized, but 2.4.6 is not
> as
> stable as ... what i write?! ... i wrote it above :-)


Keep in mind that both CI and SSI are pre-alpha. The instabilities in
2.4.6 may not be significantly greater than any problems lurking in our
own code. Of course, we would prefer to be on a stable base. ;)


> 
> Let me know what you think about my comments! :-)
> 

Thanks for the feedback!


> --
> 
> Kind regards
>         Marc-Christian Petersen
> 
> Linux-Systeme GmbH
> Hinseler Hof 3a, 45277 Essen
> Tel.: +49 201 - 85 85 130
> Fax : +49 201 - 75 00 1579
> D2  : +49 173 - 541 68 09
> mailto: mc...@li...
> http://www.linux-systeme.de/

-- 
Brian Watson                | "The common people of England... so 
Linux Kernel Developer      |  jealous of their liberty, but like the 
Open SSI Clustering Project |  common people of most other countries 
Compaq Computer Corp        |  never rightly considering wherein it 
Los Angeles, CA             |  consists..."
                            |     -Adam Smith, Wealth of Nations, 1776

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