Re: [RFC v13][PATCH 00/14] Kernel based checkpoint/restart

On Sun, 15 Feb 2009 00:08:02 +0100 Ingo Molnar [off-list ref] wrote:

* Andrew Morton [off-list ref] wrote:

quoted

Similar to the way in which perfectly correct and normal kernel
sometimes has to be changed because it unexpectedly upsets the -rt
patch.

Actually, regarding -rt, we try to keep that in two buckets:

 1) Normal kernel code works but is unclean or structured less
    than ideal. In this case we restructure the mainline code,
    but that change stands on its own four legs, without any
    -rt considerations.

 2) Normal kernel code that is clean - i.e. a change that only
    matters to -rt. In this case we dont touch the mainline code,
    nor do we bother mainline.

Do you know any specific example that falls outside of those categories?

It happens fairly regularly.  Problems with irqs-off regions, problems
with preempt_disable() regions (came up just yesterday with a patch from
Jeremy).

Plus some convert-to-sleeping-lock conversions over the years which
weren't obviously needed in mainline.  Or which at least had -rt
motivations.  But that's different.





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