[Qemu-devel] Re: [PATCH 0/6] Make hpet a compile time option

[Jan Kiszka]

Juan Quintela wrote:
>>> We already have to disable hpet for 5.4 (1 year ago).  It was done with
>>> a local hack because it was supposed that for next big release it would
>>> have been fixed.
>> But this remains a RHEL issue. Redhat decided to compile out features
>> that are unsupported, others seem to handle this differently.
> 
> And then, everybody has a different hack to disable the features that
> they don't need.  Instead of doing a local hack, we do a patch that
> allows anyone to disable HPET if it sees fit.

So far I only know of precisely one user that wants to disable x86
platform devices at build-time.

> 
>>> Here we are, and device is still not fixed, what to do?  Another local
>>> patch?  Just get upstream to integrate a sane way to disable it and let
>>> in enable by default?
>> Let's start with listing your requirements to no longer disable HPET.
> 
> It is not stable at this point in time :-(  Running with --no-hpet is
> better than without it in all our testing.  If we have to ask/modify
> everything to use --no-hpet, we can also compile-out it.
> 
>> That would already help us to asses how long !CONFIG_HPET would actually
>> be of any use at all. I'm yet optimistic that we can resolve most if not
>> all remaining concerns for 0.13 - and CONFIG_HPET would at best be 0.13
>> material anyway.
> 
> At this very point in time:
> - it is not stable

Well, that is helpful.

> - lack irq-reinjection when missing ticks

That is more helpful.

I just reworked the RTC regarding this, I guess it will be
straightforward to address it in the HPET too.

> 
> (I was not the one debugging/testing this so I don't have more details,
> but can ask for them).  So, it is not stable enough yet.

HPET is a fairly small device, a few hundred lines of code, only a few
ugly platform dependencies, but that's it already. I bet it could have
been fixed by now if someone just started by the time the tests reported
"it is not stable enough".

Jan

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