Messages in this thread | | | From | Joe Lawrence <> | Subject | Re: [PATCH 1/2] docs/livepatch: Add new compiler considerations doc | Date | Wed, 22 Jul 2020 13:03:03 -0400 |
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On 7/21/20 7:04 PM, Josh Poimboeuf wrote: > On Tue, Jul 21, 2020 at 12:14:06PM -0400, Joe Lawrence wrote: >> Compiler optimizations can have serious implications on livepatching. >> Create a document that outlines common optimization patterns and safe >> ways to livepatch them. >> >> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com> > > There's a lot of good info here, but I wonder if it should be > reorganized a bit and instead called "how to create a livepatch module", > because that's really the point of it all. >
That would be nice. Would you consider a stand-alone compiler-optimizations doc an incremental step towards that end? Note that the other files (callbacks, shadow-vars, system-state) in their current form might be as confusing to the newbie.
> I'm thinking a newcomer reading this might be lost. It's not > necessarily clear that there are currently two completely different > approaches to creating a livepatch module, each with their own quirks > and benefits/drawbacks. There is one mention of a "source-based > livepatch author" but no explanation of what that means. >
Yes, the initial draft was light on source-based patching since I only really tinker with it for samples/kselftests. The doc was the result of an experienced livepatch developer and Sunday afternoon w/the compiler. I'm sure it reads as such. :)
> Maybe it could begin with an overview of the two approaches, and then > delve more into the details of each approach, and then delve even more > into the gory details about compiler optimizations. >
Up until now, the livepatch documentation has danced around the particular creation method and only described the API in abstract. If a compiler considerations doc needs to have that complete context then I'd suggest we reorganize the entire lot as a prerequisite.
> Also the kpatch-build section can reference the patch author guide which > we have on github. >
Good point. I think there are a few kpatch-specific implications (sibling call changes maybe) to consider.
-- Joe
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