[PATCH 2/3] winevulkan: Implement extension faking mechanism

[Joshua Ashton]

To add on about the layer thing, not removing random unsupported pNext 
elements has and will break layers like RenderDoc and OBS and 
potentially drivers down the line.

The typical pattern I see is
if (info->pNext->sType == VK_STRUCTURE_TYPE_MY_UNSUPPORTED_STRUCTURE_FROG)
{
#ifdef _WIN32
	// Handle whatever this is...
	info->pNext->...
#else
	// Uh oh! Something went wrong here...
	abort(1);
#endif
}

The problem here is that the structure type is still defined in 
vulkan_core.h despite the structs, etc being defined in vulkan_win32.h 
which causes this pattern.

Many Layers (and potentially drivers) do stuff this, and not filtering 
out the pNexts will break them.
- Joshie 🐸✨

On 10/14/20 1:02 AM, Joshua Ashton wrote:
> Zeb, it's in vulkan_win32.h.
> You can't include it on Linux or any other platform for that matter.
> If you read the xml, it's marked as being `platform="win32"`.
> It's a Windows extension.
> 
> To move it out of there on a Vulkan level, we'd need to make a sequel 
> and different platform-specific extensions.
> Inherently making this version unsupportable in non-Windows drivers.
> 
> It makes more sense to read the line of VK_KHR_win32_surface support 
> more as if you want surfaces (ie. not headless) than focusing on the 
> platform part of things.
> 
> - Joshie 🐸✨
> 
> On 10/14/20 12:37 AM, Georg Lehmann wrote:
>> On 14.10.20 01:23, Zebediah Figura wrote:
>>> On 10/13/20 4:54 PM, Joshua Ashton wrote:
>>>> Figured I should add the reason why, is because just passing it through
>>>> will cause the device to fail to be created because nobody supports
>>>> VK_EXT_full_screen_exclusive on Linux.
>>> Sure, but they could.
>>>
>>>> It's an entirely Windows-centric extension.
>>> Well, no, it's not really, but it does include some API-level
>>> integration with win32 monitors *if* KHR_win32_surface is supported. In
>>> that case, as far as I can see, we don't even need to do anything,
>>> because the VkSurfaceFullScreenExclusiveWin32InfoEXT structure would
>>> just be ignored.
>>
>>
>> No, according to the vulkan spec a 
>> VkSurfaceFullScreenExclusiveWin32InfoEXT is illegal in any chain 
>> unless the full screen + win32 surface exts are enabled. In practice, 
>> this will break layers like renderdoc. So we would still need code to 
>> remove that struct from pNext chains.
>>
>>
>> Georg
>>
>>
>>> Not that this necessarily means that lower-level drivers should be the
>>> ones to implement the extension, but if nothing else, this information
>>> isn't present at all in the patch.
>>>
>>> Also, do we really need a generic mechanism for this, wired into
>>> make_vulkan? Can't we just handle this extension specially in
>>> wine_vk_device_convert_create_info()?
>>>
>>>> - Joshie 🐸✨
>>>>
>>>> On 10/13/20 10:42 PM, Joshua Ashton wrote:
>>>>> winex11/winemac only does this for instance extensions.
>>>>>
>>>>> VK_EXT_full_screen_exclusive is a device extension.
>>>>>
>>>>> - Joshie 🐸✨
>>>>>
>>>>> On 10/13/20 10:35 PM, Zebediah Figura wrote:
>>>>>> Why not do this the normal way, i.e. by modifying the code in winex11
>>>>>> and winemac?
>>>>>>
>>>>>> Also, what's the point of faking the extension like this? Why not 
>>>>>> just
>>>>>> pass it through?
>>>>>>
>>>
>>