Re: [Xen-devel] [PATCH v1 1/3] livepatch: Add local and global symbol resolution.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.06.17 at 17:59, <konrad.wilk@xxxxxxxxxx> wrote:
> Our mechanism when deploying livepatches is to replace the loaded
> livepatch with another one. Which means we only have on livepatch
> applied and during the upgrade process have to load another one.

I think this is the main problematic part here: You're trying to fix one
use case (single patch being replaced every time) while - afaict - you
break the other one (multiple stacked patches). For your case,
wouldn't it be sufficient to load the patch with some flag indicating
that all symbol handling (resolution as well as insertion) should only
consider the main image? Of course with that flag, a plain "apply"
would need to fail as long as there's any other patch loaded.

The downside of this is that it would special case things a little too
much for my taste. For example I'd expect to also be able to have
a couple of stacked patches and replace just the topmost one(s).
That would require more than a boolean flag to tell which symbols
to consider and which to ignore.

Jan


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