[PATCH 2/3] modesetting: add dynamic connector hotplug support (MST) (v2)

[Dave Airlie]

On 14 April 2015 at 13:12, Keith Packard <keithp at keithp.com> wrote:
> Dave Airlie <airlied at gmail.com> writes:
>
>> So we hot unplug, we remove the output XID from the server, in
>> parallel the client does an operation with the output XID it has
>> gotten already, and still believe is valid, and it gets BadMatch, and
>> since hardly anyone handles X errors it falls over.
>
> Yeah, I was curious if you'd found an actual race condition that
> couldn't be solved by correctly written applications. Sounds like it's
> just 'buggy' clients.
>
> Given that there just aren't that many applications which deal with
> RandR objects, it's pretty tempting to let them experience reality for a
> year or so and expect that they'll get fixed.
>
> As I said, the alternative would be to amend the spec to say that
> outputs may get added, but will never go away. That would enshrine their
> behavior as compliant, and ensure that we'd never break them in the
> future.
>
> Frankly, I think I'd probably be OK with either plan, the only one I'm
> not up for is supporting both modes with a configuration parameter that
> no-one in their right mind would enable.

I'm sort of happy to just enshrine the outputs cannot be destroyed behaviour,

But I do wonder how many things would need fixing, it might just be mutter
and a few things like that, though if gtk falls over then we should
probably leave things alone.

Aaron, any ideas on how prevalent the issue is, or if nvidia care enough, since
I took the option from you!

Dave.