On the Steam Frame the game crashed in Turnip while Dawn recorded an eye
render pass, reading an unmapped address. Turnip reads a density map through
a host mapping of its memory taken at bind time, and the maps were
sub-allocated from blocks that Dawn's buffer upload fast path maps and
unmaps. A dedicated allocation is never mapped or unmapped by Dawn.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019HBRGKTE1GnN2ah8gcZKr3
- Eyes render under a VK_EXT_fragment_density_map: full rate around each eye's forward direction,
2x2 then 4x4 pixel blocks towards the edges ([vr] foveation = off|low|medium|high, default off).
XR_FB_foveation cannot help here: the runtime's maps only shape passes drawing into its
swapchain, and the eyes reach it through a copy.
- aurora-main/patches/dawn/aurora_fdm.inc: Dawn enables the extension only on request and for
dynamic rendering, flags every render pipeline, and chains an immutable RG8 map into any pass
whose first color attachment is a view bound to one (ABI: include/aurora/dawn_fdm_abi.h).
- android/Build-QuestDawn.ps1 builds the pinned Dawn revision with those patches for arm64
(dawn-build CI flags, protobuf off) into a cached package; Build-Quest.ps1 links it
(-StockDawn opts out) and AuroraDawnProvider.cmake enables the ABI from its manifest.
- lib/gfx/foveation.hpp generates the maps (32 px per texel, densities 255/127/63); an eye is
foveated only when single_pass_eyes draws it in one render pass. Menus never are.
- Live level from the headset panel's VR tab and the launcher; the launch decides whether the
device has maps. debug.wiicompiled.foveation and debug.wiicompiled.fdm for A/B.
- Tests: Foveation cases in gx_fifo_tests, mkw_vr_config_tests. Docs: OPENXR.md, quest-port.md.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude