Re: [PATCH v2 1/6][4.16?] x86/x2APIC: defer probe until after IOMMU ACPI table parsing

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Jan Beulich writes ("Re: [PATCH v2 1/6][4.16?] x86/x2APIC: defer probe until 
after IOMMU ACPI table parsing"):
> On 05.11.2021 16:47, Ian Jackson wrote:
> > This part confused me.  Under what circumstances would we backport
> > this ?  AIUI it would be backporting a potentially-fragile and
> > not-readily-testable bugfix, for a theoretical scenario with a
> > straightforward workaround.
> 
> Well, I've said "candidate" for this very reason: To me, every bug
> fix is a candidate. Whether risks outweigh the potential benefits is
> then influencing whether to _actually_ take the change. A reason to
> take it despite the available workaround might be that
> "straightforward" doesn't also mean "obvious" here. IOW once you
> know what to do, doing so is easy. But one first needs to arrive
> there.

Could we not do a smaller fix that would print something in the boot
output, mabye ?  That would be a lower risk change.

So far, I think the tradeoff here isn't looking very good: a risk of
unclear magnitude for many users, vs a hard crash at boot for a set of
users we believe to be empty.

As ever, feel free to contradict me if I have the wrong end of one of
the many sticks here...

Ian.