[PATCH v1 5/7] docs: mark intention to deprecate TCG tracing functionality

[Alex Bennée]

Daniel P. Berrangé <berrange at redhat.com> writes:

> On Wed, May 05, 2021 at 11:41:46AM +0100, Alex Bennée wrote:
>> 
>> Alex Bennée <alex.bennee at linaro.org> writes:
>> 
>> > Daniel P. Berrangé <berrange at redhat.com> writes:
>> >
>> >> On Wed, May 05, 2021 at 10:22:57AM +0100, Alex Bennée wrote:
>> <snip>
>> >>> +TCG introspection features
>> >>> +--------------------------
>> >>> +
>> >>> +TCG trace-events (since 6.1)
>> >>> +''''''''''''''''''''''''''''
>> >>> +
>> >>> +The ability to add new TCG trace points has bit rotted and as the
>> >>
>> >> When you say this "has bit rotted", just how bad is the situation ?
>> >>
>> >> Is the TCG tracing still usable at all, or is is fully broken
>> >> already ?
>> >
>> > Well patches 6/7 got it working for generic TCG things. I haven't been
>> > able to get the architecture one working but I suspect that is some sort
>> > of interaction between the per-arch trace header generation that I
>> > haven't quite figured out yet.
>> 
>> Ahh it's since 7609ffb919 (trace: fix tcg tracing build breakage) which
>> limited tcg/vcpu events to the root trace-events file.
>
> That commit is from release 2.10.0.
>
> The other commit mentioned in patch 6 (73ff061032) is from 2.12.0.
>
> So no one has been able to use this feature for 3+ years already.
>
> Is it actually worth fixing and then deprecating for 2 releases before
> deleting, as opposed to just deleting the broken code today on basis
> that it can't have any current users ?

Well I can get it up and running with the aforementioned patches and it
seems reasonable to give some notice. I'm happy to defer to Stefan here
though as it's his sub-system.

>
> Regards,
> Daniel


-- 
Alex Bennée