a733-powervr-fex

Patches, recipes, and hard-won findings for getting the PowerVR BXM-4-64 GPU and x86 emulation working on the Allwinner A733 (sun60iw2) — as shipped on the Radxa Cubie A7A / A7S boards.

Branches: this is the trixie / kernel 6.6 line (Debian 13, kernel 6.6.x-aw2511). The original Debian 11 / kernel 5.15 work lives on the bullseye branch. They are different OS + kernel + Mesa stacks; cross-check the Tested environment table below before reproducing.

This branch is the result of an extended bring-up on a Cubie A7A running Debian 13 (trixie) on the 6.6 BSP. It documents what genuinely works — including GPU-accelerated Direct3D 9/10/11, GPU OpenGL via zink, and Windows apps via Hangover — the recipes to reproduce it, and — just as importantly — the walls that are not crossable on the shipped vendor stack and why (the big one: a live GPU-composited desktop deadlocks the kernel).

Tested environment (read this before reproducing)

All findings/benchmarks here are on Debian 13 (trixie) + kernel 6.6. The bullseye branch is a different stack (Debian 11 / 5.15). Exact baseline:

Board / SoC	Radxa Cubie A7A · Allwinner A733 (sun60iw2), heterogeneous big.LITTLE — cores 0-5 LITTLE (cap 385), cores 6-7 BIG (cap 1024); max ~1716 MHz (firmware-capped; 1794 unreachable), ~6 GB LPDDR5
OS	Debian 13 (trixie) — not bullseye
Kernel	6.6.x-aw2511 (Radxa A733 BSP, pvrsrvkm out-of-tree DKMS) — not mainline
GPU	PowerVR B-Series BXM-4-64 MC1, BVNC 36.56.104.183, closed pvrsrvkm + closed libVK_IMG Vulkan blob (Vulkan 1.3.277)
Display	split: card0 = sunxi-drm (HDMI scanout) · card1/renderD128 = pvrsrvkm (render), bridged by DRM-PRIME/renderonly
Userspace GL	TWO Mesa installs (conflict) — /usr/local IMG Mesa 24.0.1 (pvr_dri, X11-only, drives the desktop, ldconfig-priority) vs system Mesa 25.0.7 (has zink+kmsro); version-incompatible, scope each per app
x86 layer	FEX-Emu (the default for x86-64 Linux ELF via binfmt) · box64 v0.4.3 (explicit-invoke)
Windows	Hangover 11.9 (wine 11.9 + FEX/box64 WoW64) · DXVK-Sarek (native arm64ec) for D3D
Vendor pkgs	img-bxm-dkms, xserver-xorg-img-bxm from the Radxa A733 repo

The dual-Mesa split is load-bearing: the desktop runs on the /usr/local IMG Mesa (X11), while zink/kmsro live in the system Mesa 25.0.7. Keep both; scope the env per use (see gpu/README.md).

Install

./install.sh          # guided: vendor fetch -> kernel patch -> GPU sway desktop (prompts each step)
./install.sh vendor   # fetch the proprietary PowerVR stack from the vendor (not bundled — see below)
./install.sh kernel   # just the pvrsrvkm PRIME patch (dry-runs first)

(The Mesa/zink build, FEX rootfs, DXVK-Sarek, and Hangover stay manual — see the per-component READMEs.)

What's here

Dir	Contents
kernel/	pvrsrvkm DRM PRIME-import patch (still applies on 6.6) + the finding that a live GPU compositor through pvrsrvkm deadlocks the kernel.
gpu/	zink OpenGL on PowerVR Vulkan (off-screen) + gpu/dxvk/: GPU-accelerated Direct3D 9/10/11 (FL 11_0) via native arm64ec DXVK-Sarek — the headline new capability.
windows/	Windows apps via Hangover 11.9 — winrun (CLI) and guirun (GUI, software-GL) launchers; verified 7-Zip / Notepad / WordPad.
fex/	FEX setup + the custom Vulkan/GLES thunks; FEX is now the default x86-64 binfmt interpreter, with trixie tuning (TSOEnabled=0 + Multiblock=1).
box64/	box64 0.4.3 (built from source) usage + the static-glibc-MT → FEX routing.
docs/FINDINGS.md	The capability matrix — every proven path and every confirmed wall, with the why. Read this first.
docs/BENCHMARKS.md	Measured numbers — CPU, FEX/box64 overhead, the D3D draw-call / fill-rate characterization.

Capabilities at a glance (trixie)

• x86 / x64 Linux → FEX by default (binfmt); box64 0.4.3 on explicit invoke. Single-thread emulation reaches ~71% (FEX-tuned) / ~64% (box64-tuned) of native on a big core.
• Windows apps (Hangover 11.9): CLI (winrun) and GUI (guirun, software GL). Verified 7-Zip, Notepad, WordPad.
• GPU Direct3D 9/10/11 (FL 11_0) via DXVK-Sarek → PowerVR Vulkan (d3drun): instancing, compute, render-to-texture, BC1-5 textures, depth/MRT, windowed present. (D3D12 infeasible; geometry/tessellation/MSAA not native.)
• GPU OpenGL via zink → PowerVR Vulkan (glrun): off-screen only (GLES2/GL2.1 class).
• NOT possible: a GPU-accelerated desktop — a live compositor on pvrsrvkm hard-hangs the kernel. The desktop stays software-rendered. See docs/FINDINGS.md.

Benchmarks (highlights)

Full tables in docs/BENCHMARKS.md. Headlines (trixie):

• CPU single-thread (sum-ms CPU bench, big core): native 5488 / box64-tuned 8564 (~64% of native) / FEX-tuned 7746 (~71% of native).
• box64 0.4.3 built from source: clone3 fixed, ~9% faster than the Debian 0.3.4; CALLRET=1 + SAFEFLAGS=0 ≈ -15% on the CPU bench.
• FEX tuning: TSOEnabled=0 + Multiblock=1 ≈ -7% on the CPU bench (load-bearing knob is TSO-off).
• GPU D3D11 (DXVK-Sarek → PowerVR): instancing ~370k tris/s; trivial windowed present ~227 fps (~530 fps for clear-only); the draw-call submission ceiling is ~1000–1100 PSO-swap-bound draws/s of distinct pipeline state — a realistic textured/depth frame is GPU-fill-bound, not emulation-bound.
• GPU OpenGL (zink, off-screen): glmark2-es2 --off-screen = 661.

⚠️ What can't be redistributed here — and the workaround

This repo is only open / original work (patches, scripts, docs). It cannot legally include the proprietary pieces — but every one of them is fetchable from its official source, so the workaround is "install script pulls from the vendor; this repo layers the patches on top." Nothing is bundled here.

Can't ship here	Where it comes from	How the workaround gets it
PowerVR userspace + firmware — libVK_IMG, libsrv_um, libEGL, rgx.fw.* (package: xserver-xorg-img-bxm)	Radxa / Imagination vendor channel	install.sh vendor installs the vendor .deb from your configured source
img-bxm-dkms kernel module source	Radxa apt repo	apt-get install img-bxm-dkms, then our patch (kernel/) on top
DXVK-Sarek / Hangover / wine	their own upstreams	build/install yourself (see gpu/dxvk/, windows/)
FEX x86 rootfs, Steam / Chrome / Windows apps	you build / their vendors	build the rootfs; install apps into it yourself

So the model is patch + recipe + fetch-from-vendor — we never host the closed bits.

Honest summary

The GPU is fully usable per-workload — Vulkan, GPU D3D9/10/11, GL via zink (off-screen), windowed-present. It cannot drive a GPU-composited desktop: a live compositor on pvrsrvkm deadlocks the kernel (mutex spin-on-owner in IRQ → power-cycle). That ceiling is the closed kernel driver and is only liftable by a fixed pvrsrvkm / mainline drm/imagination (not present for A733 on this kernel). The desktop stays on software-rendered X11. See docs/FINDINGS.md for the full matrix.

Contributing — this is meant to be a living baseline

The point of publishing is so others can reproduce, test, optimize, and extend — and push their findings back. Concretely:

• Reproduce the numbers: harnesses are in bench/; add your board's results to RESULTS.md.
• Challenge a finding: docs/FINDINGS.md is dated observations, not gospel — if a "wall" falls for you (newer DDK, fixed pvrsrvkm, mainline), that's a great PR.
• Open problems / help wanted: the GPU-desktop kernel deadlock, the draw-call submission ceiling, general VS-as-compute for the GS-emulation path, D3D12. See CONTRIBUTING.md.

Issue templates and a PR checklist are set up. Rule: no proprietary blobs, rootfs, app binaries, or secrets in commits.

Acknowledgments

Built on the Linux kernel DRM subsystem, the Imagination PowerVR DDK, the Radxa / Allwinner BSP, FEX-Emu, box64, Mesa/Zink, DXVK / DXVK-Sarek, Hangover and wine — plus the wider A733 community. Full list + links in ACKNOWLEDGMENTS.md.

License

Original code/patches/scripts here are MIT (see LICENSE). They are intended to be applied on top of vendor/upstream sources that carry their own licenses; obtain those from their respective sources.