Re: ARM64 Livepatch based on SFrame

["Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>]

On 12/15/23 07:04, Mark Rutland wrote:
> On Thu, Dec 14, 2023 at 02:49:29PM -0600, Madhavan T. Venkataraman wrote:
>> Hi Mark,
> 
> Hi Madhavan,
> 
>> I attended your presentation in the LPC. You mentioned that you could use
>> some help with some pre-requisites for the Livepatch feature.
>> I would like to lend a hand.
> 
> Cool!
> 
> I've been meaning to send a mail round with a summary of the current state of
> things, and what needs to be done going forward, but I haven't had the time
> since LPC to put that together (as e.g. that requires learning some more about
> SFrame).  I'll be disappearing for the holiday shortly, and I intend to pick
> that up in the new year.
> 
>> What would you like me to implement?
> 
> I'm not currently sure exactly what we need/want to implement, and as above I
> think that needs to wait until the new year.
> 

OK.

> However, one thing that you can do that would be very useful is to write up and
> report the GCC DWARF issues that you mentioned in:
> 
>   https://lore.kernel.org/linux-arm-kernel/20230202074036.507249-1-madvenka@linux.microsoft.com/
> 
> ... as (depending on exactly what those are) those could also affect SFrame
> generation (and thus we'll need to get those fixed in GCC), and regardless it
> would be useful information to know.
> 
> I understood that you planned to do that from:
> 
>   https://lore.kernel.org/linux-arm-kernel/054ce0d6-70f0-b834-d4e5-1049c8df7492@linux.microsoft.com/
> 
> ... but I couldn't spot any relevant mails or issues in the GCC bugzilla, so
> either I'm failing to search hard enough, or did that get forgotten about?
> 

Yeah. I had notes on that. But I seem to have lost them. I need to reproduce the
problems and analyze them again which is not trivial. So, I have been procrastinating.

I am also disappearing for the rest of this year. I will try to look at it in the
new year.

>> I would also like to implement Unwind Hints for the feature. If you want a
>> specific format for the hints, let me know.
> 
> I will get back to you on that in the new year; I think the specifics we want
> are going to depend on other details above we need to analyse first.
> 

OK.

For now, I will implement something and send it out just for reference. We can revisit
this topic next year sometime.

Thanks.

Madhavan