panvk-bifrost/research/r6_r7_mali_g52_feature_audit_2026-05-24.md

Mali-G52 r1 MC1 Feature Delta — r6/r7 Candidate Audit (2026-05-24)

Multi-language research (EN/CN/RU/KO/JA/Bayrisch) into HW capabilities of Mali-G52 r1 MC1 vs what Mesa 26.0.6 panvk advertises. Goal: identify candidate downstream patches (r6/r7) in the same shape as r1-r5.

Hardware

• ARM Mali-G52 r1 MC1 (Bifrost gen-2, PAN_ARCH 7)
• Single shader core, 800 MHz peak
• Shipped in RK3566 (PineTab2, PineNote, Quartz64-B)
• TBDR architecture with tile memory (~16 KB per shader core, 8 KB per pixel per ARM developer docs)

Authoritative sources

• ARM developer docs:
  • "Bifrost Shader Core" — developer.arm.com/documentation/102546
  • "Pixel Local Storage on Arm Mali GPUs" — ARM community blog
  • "Framebuffer Fetch in Vulkan" — ARM community blog
• chipsandcheese.com Bifrost-G52 teardown (May 2025)
• Mesa 26.0 / 26.1 release notes
• Christian Gmeiner's "PanVK Extension Sprint" blog post (Apr 2026)
• Rockchip RK3566 datasheet (boardcon mirror)

Confirmed HW-supported features under-exposed by upstream Mesa (PAN_ARCH < 9 gates)

These are candidate flips in the same shape as r1..r5.

High-confidence pure-software flips (small-scope r6 candidates)

Feature	Why HW-doable	Why panvk hides it
VK_EXT_pipeline_robustness	Software-level robustness selector; composes on top of our r1 KHR_robustness2 flip	Not advertised on PAN_ARCH<10. No HW dep.
VK_EXT_depth_clip_control / VK_EXT_depth_clip_enable	Mali has LOW_DEPTH_CLAMP / HIGH_DEPTH_CLAMP registers per Gmeiner's blog	Just not wired in panvk_vX_physical_device.c
VK_EXT_provoking_vertex	Panfrost GL already supports it on Bifrost; just a selector	Not wired
VK_EXT_load_store_op_none / VK_KHR_load_store_op_none	Pure Vulkan spec relaxation; no HW change	Not advertised
VK_EXT_pageable_device_local_memory / VK_EXT_memory_priority	Pure software; UMA-friendly	Not advertised

Medium-confidence HW-touch flips (need NIR plumbing, not just flag)

Feature	HW support evidence	Effort
shaderStorageImageMultisample	Bifrost ALU + tile memory can do MSAA SSBO stores per ARM blob exposure	NIR dirty-bit work
shaderStorageImageReadWithoutFormat / WriteWithoutFormat	Bifrost LD/ST has typed + untyped paths; Mesa 25.1 flipped shaderStorageImageExtendedFormats already	NIR pass refinement
VK_EXT_extended_dynamic_state3 (subset)	Each piece is dynamic-state plumbing, not new HW	Per-piece evaluation

High-confidence HW-real flips (multi-week r7 territory)

Feature	HW evidence	Engineering scope
VK_EXT_rasterization_order_attachment_access	TBDR tile memory exists; Panfrost GL implements FB fetch (Mesa MR !5755)	Real PanVK FB-fetch plumbing — port from GL path
VK_KHR_dynamic_rendering_local_read	Maps to FB fetch / tile memory which G52 has	Pairs with the above; design together
Tile-image / pixel-local-storage Vulkan exposure	Mali tile memory ~16 KB per SC; ARM exposes PLS GLES-only natively	Substantive driver feature

Confirmed HW limitations (NOT candidates)

These are silicon-absent on G52, not patch surface:

• sparseResidency* — Bifrost MMU lacks sparse residency model (Mesa gates to v10+)
• subgroupSize ≥ 16 / advanced subgroup ops — Bifrost is 4- or 8-wide warps
• VK_EXT_nested_command_buffer — needs CSF (v10+)
• VK_KHR_shader_untyped_pointers — explicit "Bifrost has issues" per Gmeiner blog
• Video codec extensions — Mali has no video silicon (hantro VPU territory; covered by mesa-panvk-bifrost-video sibling)
• shaderInt64, 64-bit atomics, mesh shaders, hardware ray tracing, fragment shading rate — all silicon-absent

Needs HW probing (uncertain)

• sampleRateShading — Vulkan 1.0 mandatory; if currently false on v7 it's likely a flip candidate
• VK_EXT_sample_locations — Bifrost rasterizer has programmable sample positions per ARM docs
• dualSrcBlend on v7 — Panfrost GL supports dual-source per Icecream95 notes; PanVK status unclear
• VK_EXT_filter_cubic — unclear if Bifrost texturing has cubic sampler natively

Test path: run targeted dEQP-VK subsets against the existing r5 driver and observe NotSupported vs Fail distribution; cross-reference with Panfrost GL coverage of the same hardware paths.

Multi-language source notes

• 🇨🇳 Chinese: Rockchip RK3566 datasheet (boardcon mirror) confirms Mali-G52 2EE, Vulkan 1.1, OpenCL 2.0, AFBC/ASTC. Zhihu article zhuanlan #480270449 confirms panvk historic non-conformant status — background, no new HW info.
• 🇷🇺 Russian: opennet.ru posts 62674 / 55845 confirm PanVK conformance restricted to v10+ (G610/G310 only), G52 explicitly non-conformant. Matches English sources.
• 🇯🇵 Japanese: 0 useful Mali-G52-specific hits across Qiita / Hatena.
• 🇰🇷 Korean: 0 hits. RK3566 not deployed in Korean SoC ecosystem; Korean Mali experience is via Exynos with different gen.
• 🇩🇪 Bayrisch: 0 Stammtisch threads on Mali-G52. Recorded for posterity — the void where Bavarian GPU forums should be is now established as a load-bearing fact.

The leaked ARM Software Developer's Manual

Not found in the wild. Multiple targeted searches (English/Russian/Chinese) for "Mali-G52 Software Developer Manual PDF leak datasheet" returned only the public ARM developer-portal product page and GitHub kernel-driver mirrors (batocera-linux/mali-bifrost, LibreELEC/mali-bifrost). The Bifrost ISA reference is reverse-engineered (Panfrost team's src/panfrost/compiler/), not vendor-published.

Implication: Mesa's own source is the authoritative "what's possible on Bifrost" reference. For future iterations, grep src/panfrost/compiler/bi_test_*.c and panvk feature gates (PAN_ARCH < N checks) before chasing leaks.

Confirms iter18's earlier finding: 0 Vulkan symbols in vendor libmali-bifrost-g52-*.so. The mali-bifrost-g52 has no proprietary Vulkan implementation anywhere — Panfrost is the only Vulkan driver this hardware will ever have.

Top 3 ranked recommendations

1. r6 = VK_EXT_pipeline_robustness alone — smallest scope, real consumer value (DXVK/vkd3d/Wine D3D translation paths). 1-line panvk_vX_physical_device.c flip.
2. r6.5 = small-bundle (depth_clip_control + depth_clip_enable + provoking_vertex + load_store_op_none) — each is a separate small flip; together they meaningfully widen the D3D-to-Vulkan translation layer matrix.
3. r7 = FB-fetch / tile-image extensions paired (VK_EXT_rasterization_order_attachment_access + VK_KHR_dynamic_rendering_local_read) — multi-week real engineering iteration. Phase-0-substrate first to map Mali tile-memory primitives to Vulkan attachment-access semantics. Unlocks deferred-shading paths without bouncing through main memory.

Out of scope

• Upstreaming any of these — per feedback-no-upstream-proposals our channel is marfrit-packages downstream.
• Chasing the leaked manual further — diminishing returns vs reading Mesa source.

🤖 Research compiled by Claude Opus 4.7 (general-purpose subagent + main thread) on 2026-05-24.