Related to #3224
Previously, Ghostty used a static API for async event handling: io_uring
on Linux, kqueue on macOS. This commit changes the backend to be dynamic
on Linux so that epoll will be used if io_uring isn't available, or if
the user explicitly chooses it.
This introduces a new config `async-backend` (default "auto") which can
be set by the user to change the async backend in use. This is a
best-effort setting: if the user requests io_uring but it isn't
available, Ghostty will fall back to something that is and that choice
is up to us.
Basic benchmarking both in libxev and Ghostty (vtebench) show no
noticeable performance differences introducing the dynamic API, nor
choosing epoll over io_uring.
Mode 2048 and CSI 14 t are size report control sequences which contain
the text area size in pixels. The text area is defined to be the extents
of the grid (rows and columns). Ghostty calculates the available size
for the text area by setting the available padding, and then filling as
much of the remaining space as possible. However, if there are remainder
pixels these are still reported as part of the text area size.
Pass the cell_size geometry through so that we can always report the
correct value: columns * cell width and rows * cell height.
