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SubjectRe: [PATCH v0 2/3] livepatch: update documentation/samples for callbacks
On Tue, 27 Feb 2018, Joe Lawrence wrote:

> On 02/27/2018 07:36 AM, Miroslav Benes wrote:
> > On Fri, 23 Feb 2018, Joe Lawrence wrote:
> >
> >> [ ... snip ... ]
> >>
> >> +If a livepatch is replaced by a cumulative patch, then only the
> >> +callbacks belonging to the cumulative patch will be executed. This
> >> +simplifies the livepatching core for it is the responsibility of the
> >> +cumulative patch to safely revert whatever needs to be reverted. See
> >> +Documentation/livepatch/cumulative.txt for more information on such
> >> +patches.
> >
> > s/cumulative/atomic replace/ almost everywhere?
> >
> > 'Documentation/livepatch/cumulative.txt' should be
> > 'Documentation/livepatch/cumulative-patches.txt' and we may rename it
> > atomic-replace-patches.txt. I don't know. Cumulative patches forms a
> > subset of atomic replace patches in my understanding. The feature itself
> > is more general. Even if practically used for cumulative patches only. But
> > it is for you and Petr to decide.
>
> Hi Miroslav,
>
> Thanks for reviewing!
>
> I guess I'm a little confused about the distinction here.
>
> I understood a "cumulative-patch" to mean that it would contain the sum
> of all changes. So instead of this:
>
> patch 1 = A
> + patch 2 = B
> + patch 3 = C
> -----------------------
> net = A + B + C
>
> We can group all of the changes together into a single cumulative-patch
> for the same net effect:
>
> patch 1 = A -replaced by-
> patch 2 = A + B -replaced by-
> patch 3 = A + B + C

Yes.

> I assumed this would also mean to include any reverted changes as well.
> So in the example above, if change C needed to be reverted, then:
>
> patch 4 = A + B
>
> and that would still be considered a "cumulative-patch".

Ah, ok. This is where we differ. I didn't consider this to be a cumulative
patch. But I understand your reasoning.

Miroslav

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