"AMD's Windows driver offers no MAILBOX" is the premise the FIFO glass gate is
built on, and it has been carried in a code comment rather than measured. Present
modes are a property of the (surface, device) pair — they vary by platform
surface, driver version and fullscreen state — so the only way to settle it is to
read them back from real machines. One unconditional log line makes every field
log answer the question.
First reading, .21 (NVIDIA 610.43.03, GNOME/Wayland):
surface present modes available=[MAILBOX, 1000361000, FIFO]
Two things fall out. No IMMEDIATE and no FIFO_RELAXED on this surface, which is
why a PUNKTFUNK_PRESENT_MODE=immediate run reported mode=fifo — the pin was not
offered and the ladder fell through; previously that looked like a puzzling
result and is now evidence. And 1000361000 is
VK_PRESENT_MODE_FIFO_LATEST_READY_EXT: FIFO's tear-free vblank pacing that
presents the LATEST READY image instead of draining a queue — the driver-native
version of what the glass gate emulates in software, and a candidate to replace
it wherever the driver exposes it (needs VK_EXT_present_mode_fifo_latest_ready
enabled at device creation, so a work package rather than a tweak).
Also documents PUNKTFUNK_VRR_FIFO, which the previous commit introduced without
a docs entry.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
enricobuehlerandClaude Opus 5
e08474d96d