gamescope's built-in PipeWire node has always been SDR-only: it offers BGRx
and NV12, and `paint_pipewire()` hardcodes a Gamma-2.2 composite with the SDR
screenshot LUT set. So an HDR game reaches punktfunk already tone-mapped down,
and the whole gamescope backend streams 8-bit no matter what the client can
decode. Games CAN render HDR on a headless gamescope today — only the capture
half is missing.
Carry the two patches that close it (packaging/gamescope/patches): the node
additionally offers `xRGB_210LE`/`xBGR_210LE` with MANDATORY SMPTE ST.2084 +
BT.2020 props, mapped to the same 10-bit capture texture the HDR AVIF
screenshot path already allocates, and `paint_pipewire()` composites into them
with the HDR screenshot LUTs + `EOTF_PQ` — which is exactly the in-tree
`bHDRScreenshot` branch. The new formats are listed LAST, so every existing
consumer keeps negotiating the 8-bit stream bit-for-bit. Offered upstream
against ValveSoftware/gamescope#2126.
Ship it as `punktfunk-gamescope`, beside the distro's own binary rather than
replacing it: a Bazzite sysext payload (`build-sysext.sh --gamescope`, which
refuses a binary without the marker), an Arch package, a nix derivation +
`services.punktfunk.host.gamescopeHdr`, and one distro-agnostic build script
the rest call.
The second patch stamps `+pfhdr1` into the `--version` banner. That is not
cosmetic: punktfunk fixes a session's bit depth in the Welcome, before the
display exists and with no way to take it back, so its capability answer has to
be a static property of the binary it will spawn.
enricobuehler
d6818263ce