Error messages from Mesa during startup

[geofft]

First things first - this project looks very cool!

I'm on an Ubuntu 25.04 aarch64 live CD running inside macOS Virtualization.framework (using my homegrown VMM, but I expect this would repro this with any Virtualization.framework client that sets up a display including the official sample app, and possibly even with qemu with virtio-gpu). If I enable the default shader, I get a bunch of error messages on startup, output to my terminal briefly before Tattoy redisplays the screen. It seems they go to stderr, so I was able to redirect them and see what they said:

MESA: info: virtgpu backend not enabling VIRTGPU_PARAM_CREATE_FENCE_PASSING
MESA: info: virtgpu backend not enabling VIRTGPU_PARAM_CREATE_GUEST_HANDLE
MESA: error: DRM_IOCTL_VIRTGPU_GET_CAPS failed with Function not implemented
MESA: error: DRM_IOCTL_VIRTGPU_CONTEXT_INIT failed with Invalid argument, continuing without context...
MESA: error: DRM_VIRTGPU_RESOURCE_CREATE_BLOB failed with Invalid argument
MESA: error: Failed to create virtgpu AddressSpaceStream
MESA: error: vulkan: Failed to get host connection
MESA: error: DRM_VIRTGPU_RESOURCE_CREATE_BLOB failed with Invalid argument
MESA: error: Failed to create virtgpu AddressSpaceStream
MESA: error: vulkan: Failed to get host connection
MESA: error: DRM_VIRTGPU_RESOURCE_CREATE_BLOB failed with Invalid argument
MESA: error: Failed to create virtgpu AddressSpaceStream
MESA: error: vulkan: Failed to get host connection
MESA: error: DRM_VIRTGPU_RESOURCE_CREATE_BLOB failed with Invalid argument
MESA: error: Failed to create virtgpu AddressSpaceStream
MESA: error: vulkan: Failed to get host connection
MESA: error: DRM_VIRTGPU_RESOURCE_CREATE_BLOB failed with Invalid argument
MESA: error: Failed to create virtgpu AddressSpaceStream
MESA: error: vulkan: Failed to get host connection
MESA: error: DRM_VIRTGPU_RESOURCE_CREATE_BLOB failed with Invalid argument
MESA: error: Failed to create virtgpu AddressSpaceStream
MESA: error: vulkan: Failed to get host connection

First, I'm a little surprised to see that mesa_log defaults to stderr without a proper in-process way to control it, but maybe you would want to set the environment variable MESA_LOG=none or MESA_LOG_FILE pointing somewhere useful before initializing Mesa, or maybe you want to just repoint your own stderr somewhere, especially if it's pointing at the terminal.

Second, I wonder if these messages mean anything that I should do anything about, but maybe that's not a particularly Tattoy-specific question.

Screen.Recording.2025-06-13.at.11.45.01.PM.mov

[tombh]

Oh yes, good point, I have custom panic handlers that try to prevent panics getting dumped to STDERR but of course that doesn't prevent non-panic STDERR output. I can fix that. Thanks for mentioning it.

So I'm guessing shaders aren't rendering then? I wonder if using any of wgpu's (Tattoy's GPU lib) ENV vars will help. Say WGPU_BACKEND=gl? Here are all the options: https://github.com/gfx-rs/wgpu?tab=readme-ov-file#environment-variables

[geofft]

Shaders do seem to be working great despite those messages!

There were a few things that confused me:

• You have to actually turn on the shader and the minimap in the config file, you can't turn them on with keyboard shortcuts.
• Alt-t doesn't toggle the indicator in the corner until the terminal rerenders for some other reason, so I was confused about whether keyboard shortcuts were working at all.
• The built-in soft-shadows shader pays attention to the color of the current cell, but in a normal shell, the current cell is black until you type something - you will see it do something as soon as you arrow or backspace into a cell that had some text in it.

But assuming all those are intentional, it does seem to work fine. I tried out some other shaders and they also work fine.

[tombh]

• I have wondered about shortcuts to turn on various features, but haven't come across a convincing usecase yet. I imagined you just wanted to enable them to play with them? My usecase for the shaders is for adding backgrounds to my various Desktop Environment pickers. I use a simple popup terminal with fzf for things like application picker, emojis etc. So to enable shaders I use custom config per picker popup. I'm very open to adding shortcuts, I'm just curious to see how people actually use Tattoy first.
• There was a bug with ALT-t, I've released a fix in v0.1.2.
• I've also released a fix for the shaders appearing black when they shouldn't, I'm not 100% sure it fixes your issue, let me know.