Software rendering fallback

[pbsds]

A terminal is what I consider a critical piece of software. When I update my drivers I sometimes experience that ghostty refuses to start due to not being able to open a GL context. This blocks me from working until I restart. Is it possibly to add a software-rendering fallback (with warnings of course) to smoothen the impact?

[pluiedev]

I don't think it's feasible to port all of our rendering infrastructure away from OpenGL to CPU rendering à la foot. Do software rasterization layers like llvmpipe help?

[pbsds]

it would yes, it was the solution i had in mind

[mitchellh]

Yes, I developed Ghostty on Linux with llvmpipe for ~6 months while M-series processors were new and VMware enabled GPU acceleration for them. They should work.

[rhodes-b]

as another note the gpu requirements for both linux and macos are very light, not being able to create a gl context is very likely indicator of buggy gpu drivers my assumption is this relates to nvidia which ghostty can do nothing about (which would affect alot of apps?). If the solution above does not work you should install separate backup terminal if its that "critical" (what if any other bug makes your terminal unuseable?)

there is also always the tty which you can access with ctrl+alt+fn1 through fn7 if its extremely critical (your graphical env is normally logged in on tty1 so use the others in that case) <----- id say this is your answer right here in the context of criticality

on linux it requires opengl 3.3 which is ~15 years old

macos metal which goes back even to some intel macs

[pbsds]

I'm only familiar with lxterminal and gnome-terminal, neither of which display this behavour. i think neither are particularly accelerated.

[pluiedev]

GNOME Terminal is GTK 3. Could you try e.g. GNOME Console, Ptyxis, Black Box?

[rhodes-b]

Or other GPU accelerated terminals like Kitty and Foot

[pbsds]

It's likely going to be a couple of weeks before I'm in this state again, but I'll try to remember to report back 👍

[00-kat]

Or other GPU accelerated terminals like Kitty and Foot

Foot is not GPU-accelerated.

[mitchellh]

I've definitely considered this. It's possible for sure. It's even something I've considered not just making a fallback but making it so that we use the CPU renderer for the first few frames while acquiring a GPU context and resources (since that takes a few frames). Kind of crazy, but cool.

In the short term, I think having your system fallback to a software rasterizer as pluie suggested is the much more sane approach. When my GPU driver has been broken, falling back to something like llvmpipe is how I work around this. This helps many more programs work, not just Ghostty. 😄

[pbsds]

having your system fallback to a software rasterizer

How may i configure this?

[D3vil0p3r]

It would be great if this fallback could be implemented. Alacritty team faced the same issue discussed here alacritty/alacritty#128 and implemented by kchibisov/alacritty@4a6a0d6 if it could be helpful as reference

[mitchellh]

I think more data is required to make this justified. The way I see it, this has not been heavily requested or discussed, and there are great alternatives (use Alacritty or Kitty or a non-GPU terminal like foot). OpenGL 3.3 is over 15 years old now, I'm not sure we need to care too much about systems that don't support it (esp given alternatives exist). But, I'm willing to be convinced otherwise.