[Mesa-dev] [Bug 110810] Vulkan spec break: VkCommandBufferInheritanceInfo.framebuffer is NOT optional

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=110810

            Bug ID: 110810
           Summary: Vulkan spec break:
                    VkCommandBufferInheritanceInfo.framebuffer is NOT
                    optional
           Product: Mesa
           Version: unspecified
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: critical
          Priority: medium
         Component: Other
          Assignee: mesa-dev at lists.freedesktop.org
          Reporter: sebastian at sydow.homeip.net
        QA Contact: mesa-dev at lists.freedesktop.org

Created attachment 144406
  --> https://bugs.freedesktop.org/attachment.cgi?id=144406&action=edit
Renderdoc capture, see How to reproduce 2

In the Vulkan spec about VkCommandBufferInheritanceInfo it is stated that:
(https://www.khronos.org/registry/vulkan/specs/1.1-extensions/man/html/VkCommandBufferInheritanceInfo.html)

```
framebuffer optionally refers to the VkFramebuffer object that the
VkCommandBuffer will be rendering to if it is executed within a render pass
instance. It can be VK_NULL_HANDLE if the framebuffer is not known, or if the
VkCommandBuffer will not be executed within a render pass instance.
```

VkCommandBufferInheritanceInfo.framebuffer is however NOT optional on Intel and
AMD Mesa Vulkan drivers.

Effects on various drivers I could test:
- Intel HD 630 18.2.8: SEGFAULT
- Intel HD 630 19.0.1: works?
- AMD Vega m GL 18.2.8: blank screen
- AMD Vega m GL 19.0.1: blank screen
- AMD Vega 64 18.2.8: blank screen
- AMD Vega 64 19.0.1: blank screen
I could only reproduce this behaviour on Mesa drivers, not with Windows and AMD
drivers.



How to reproduce 1:
- Clone Sascha Willems Vulkan Examples and Demos repo:
https://github.com/SaschaWillems/Vulkan.git
- open examples/multithreading/multithreading.cpp
- go to line 411 and comment out:
```
// Secondary command buffer also use the currently active framebuffer
inheritanceInfo.framebuffer = frameBuffer;
```
- this will cause framebuffer to be a nullptr, aka optional



How to reproduce 2:
- get RenderDoc
https://renderdoc.org/
- open the attached file "Mesa Bug.rdc"
- in the middle select the texture viewer
- on the top in the timeline open up the two gray bars
- on the buttom inside the timeline chart you should see two triangles. These
are the draws. Selecting them will show you the expected result.
- selecting the block afterwards will make the result disappear.
- I'm expecting that RenderDoc draws the currently selected draw separately on
top of all previous draws

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