Re: [PATCH] ubsan: Introduce CONFIG_UBSAN_FATAL to panic on UBSAN failure

[Julien Grall <julien@xxxxxxx>]

On 28/11/2023 18:00, Michal Orzel wrote:
> Hi Julien,
>
> On 28/11/2023 17:14, Julien Grall wrote:
> > Hi Michal,
> >
> > On 27/11/2023 15:41, Michal Orzel wrote:
> > > Introduce the CONFIG_UBSAN_FATAL option to cater to scenarios where prompt
> > > attention to undefined behavior issues, notably during CI test runs, is
> > > essential. When enabled, this option causes Xen to panic upon detecting
> > > UBSAN failure (as the last step in ubsan_epilogue()).
> > I have mixed opinions on this patch. This would be a good one if we had
> > a Xen mostly free from UBSAN behavior. But this is not the case at least
> > on arm32. So we would end up to stop at the first error. IOW, we would
> > need to fix the first error before we can see the next one.
> Well, this patch introduces a config option disabled by default.
I understood this is disabled by default... I am pointing out that I am 
not convinced about the usefulness until we are at the stage where Xen 
is normally not reporting any USBAN error.
> If we end up enabling it for CI for reasons* stated by Andrew, then the natural 
> way
> of handling such issues is to do the investigation locally.
This will not always be possible. One example is when you are only able 
to reproduce some of the USBAN errors on a specific HW.
> Then, you are not forced
> to select this option and you can see all the UBSAN issues if you want.
See above, I got that point. I am mostly concerned about the implication 
in the CI right now.
> > So I feel it would be best if the gitlab CI jobs actually check for
> > USBAN in the logs and fail if there are any. With that, we can get the
> > full list of UBSAN issues on each job.
> Well, I prefer Andrew suggestion (both [1] and on IRC), hence this patch.
>
> *my plan was to first fix the UBSAN issues and then enable this option for CI.
That would have been useful to describe your goal after "---". With that 
in mind, then I suggest to revisit this patch once all the UBSAN issues 
in a normal build are fixed.
Cheers,

--
Julien Grall