OpenTTD: "no memory to back the GART" with the staging pool (2026-10-19)

Symptom. One of 13 OpenTTD runs since Mesa ps3.544 (20261019T102932Z-openttd-base, with NV30_STAGING_POOL_MB=24) logged five ps3rsx: no memory to back the GART (56 of 63 MiB in use) within a second, at 37683 s of uptime; bench/analysis/logscan.py flagged it as NEW. The run still finished (ended=window), nothing showed in the picture, and the other twelve runs are clean.

Cause. OpenTTD uploads an 8 MB staging buffer per frame; the 24 MB pool (Mesa 0040) and the rest of the process’s buffers reach the 63 MiB GART when something else arrives at the same moment (a second 4 MB buffer, the title screen’s textures). This is a different path from the GART-full crashes of other games: the kernel cannot get pages (CMA chunks) to back the GART, not a full aperture. The draw that asked for the buffer may have been dropped.

Fix. None needed yet. If it repeats (OpenTTD blit8 with the pool x6, dmesg watched), cap the pool at 16 MB or have the pool release on a failed allocation.