Re: [PATCH] Disable non-ABI-compliant optimisations for live patching

From: Torsten Duwe
Date: Mon Jun 27 2016 - 03:00:06 EST


On Mon, Jun 27, 2016 at 12:39:56AM +0200, Pavel Machek wrote:

> Would it be possible to document which kind of guarantees live
> patching needs from compiler?

Sure, here you go, all required guarantees:

Stick to the ABI.

> I always assumed that whoever is preparing the patch does manual
> investigation to see what needs to be changed and how, but apparantly
> that's not the case, so documentation would be good.

See above for the documentation. Imagine each architecture had a whole
hand-optimised assembler kernel. That would give some performance
improvement, right? Same issue here, only much smaller. It's ultimate
performance vs. maintainability.

HTH,
Torsten