Godot 4.0 alpha editor segfaults when browsing to import a project using lavapipe

[warriordog]

Godot version

v4.0.alpha3.official.256069eaf

System information

Xubuntu 21.04 (64-bit)

Issue description

The editor crashes with a segfault when clicking "Browse" in the Project Manager's "Import Existing Project" dialog. This happens immediately, before the file picker even opens.

Console output:

hazel@CBKLAPTOP:~/programs$ ./Godot_v4.0-alpha3_linux.64 
Godot Engine v4.0.alpha3.official.256069eaf - https://godotengine.org
Vulkan API 1.2.162 - Using Vulkan Device #0: Unknown - llvmpipe (LLVM 12.0.0, 256 bits)
WARNING: lavapipe is not a conformant vulkan implementation, testing use only.
 
Segmentation fault (core dumped)

Steps to reproduce

1. Open the godot editor to the Project Manager screen.
2. Click "Import" in the top-right corner to import a project. The "Import Existing Project" dialog will open.
3. Click "Browse" to the right of the "Project Path" field.
4. The editor immediately closes, and Segmentation fault (core dumped) is printed to the terminal.

Minimal reproduction project

No reproduction project, as this happens before any project is loaded.

[Calinou]

Do you have a Vulkan-compatible GPU? If so, does this occur when using it instead of software rendering via lavapipe?

[warriordog]

@Calinou Not on that computer. It has an Intel i7-2670QM with HD 3000 integrated graphics, which doesn't support Vulkan as far as I know. Do you just need any Vulkan GPU to test? I could try this on my main computer if that would help. It has a much more modern GTX 980 (which definitely DOES support vulkan), but it only has Windows installed so I'd need to boot an Ubuntu live USB.

[Calinou]

Do you just need any Vulkan GPU to test?

Yes, any fully Vulkan-compatible GPU will do. This excludes Intel Haswell IGPs, which are only partially Vulkan-compatible.

[akien-mga]

I can't reproduce the issue with either AMD Radeon RX Vega M or with lavapipe:

Vulkan API 1.2.0 - Using Vulkan Device #1: AMD - AMD RADV VEGAM

Vulkan API 1.2.0 - Using Vulkan Device #0: Unknown - llvmpipe (LLVM 13.0.1, 256 bits)

But @warriordog has a slightly older lavapipe, and so bug is likely related to it. It's not a fully conformant Vulkan implementation as the warning mentions. And there's an upstream issue keeping track of related problems: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3772

You could compile a debug build of Godot to have debug symbols and get a crash backtrace, which could confirm if the crash happens in lavapipe code.

[warriordog]

I think this is very likely to be an issue with lavapipe. I upgraded to Xubuntu 21.10 (which has a slightly newer version) and now the crash happens even earlier. Godot closes with a segmentation fault at around the time when it would be moving from the splash screen into the actual editor. I'm going to try and manually update to the latest version and - if I don't brick my installation - I'll report back if the problem is fixed.

[warriordog]

Well, I updated to the latest compatible version of mesa (21.3.7) and the crash still happens:

hazel@CBKLAPTOP:~/programs$ ./Godot_v4.0-alpha3_linux.64 
Godot Engine v4.0.alpha3.official.256069eaf - https://godotengine.org
Vulkan API 1.2.162 - Using Vulkan Device #0: Unknown - llvmpipe (LLVM 13.0.0, 256 bits)
WARNING: lavapipe is not a conformant vulkan implementation, testing use only.
 
Segmentation fault (core dumped)

[warriordog]

Godot 4.0 Alpha 4 is still affected, by the way:

hazel@CBKLAPTOP:~/programs$ ./Godot_v4.0-alpha4_linux.64 
Godot Engine v4.0.alpha4.official.f47097973 - https://godotengine.org
Vulkan API 1.2.162 - Using Vulkan Device #0: Unknown - llvmpipe (LLVM 13.0.0, 256 bits)
WARNING: lavapipe is not a conformant vulkan implementation, testing use only.
 
Segmentation fault (core dumped)

[warriordog]

@akien-mga I don't know how to make a debug build, but I ran under gdb and got this:

Thread 20 "Godo:lavapipe0" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffbcff9640 (LWP 4517)]
0x00007ffff064d689 in llvm::CmpInst::Create(llvm::Instruction::OtherOps, llvm::CmpInst::Predicate, llvm::Value*, llvm::Value*, llvm::Twine const&, llvm::Instruction*) () from /lib/x86_64-linux-gnu/libLLVM-13.so.1

[Calinou]

This should likely be reported to the Mesa developers (where lavapipe is maintained).

[EamonnMR]

Seeing the same issue on the latest lubuntu lts. Is gd4 just not targeting anything without Vulkan?

[Calinou]

Duplicate of #38428.

Is gd4 just not targeting anything without Vulkan?

There's an OpenGL renderer you can test with the --rendering-driver opengl3 command line argument, but many features are still missing, especially in 3D. Note that you may have to create a project from the command line (see that page's description) to bypass the project manager. See also #58927.