xf86: VGA arbiter lock on CloseScreen() still needed ?

[Michel Dänzer]

On 2025-04-29 13:13, Enrico Weigelt, metux IT consult wrote:
> Hello folks,
> 
> 
> I'm currently working on simplifying hooking into ScreenRec proc's:
> 
> Instead of anybody directly manipulating the individual proc vectors
> and forming a daisy chain, now using the generic callback mechanism
> we already have in many other places. The big difference here is that
> those callbacks are now called independently from each other, there isn't any guaranteed execution order - except that they're all been
> called until we reach the original screen proc (filled by the driver).
> 
> In most cases, that's really simple and straightforward, [...]

That contradicts my experience working on the X server code for over two decades. There are many cases where the callbacks must be executed in a specific order for correct operation. And the driver's callback can be anywhere in that order.


> When fully done, it's also now possible hook/unhook at runtime (eg.
> enable/disable extensions on the fly, etc)

That's already possible, and done.


-- 
Earthling Michel Dänzer       \        GNOME / Xwayland / Mesa developer
https://redhat.com             \               Libre software enthusiast