initial seed: retrofit campaign lineage from local working trees

panvk-bifrost campaigns (r1..r4 Vulkan compositor + r5.video1 Vulkan video decode) shipped before this repo existed; the deliverable patches live in marfrit-packages, but the reasoning chain, phase docs, and source-state evidence lived only in local working trees on the development host. This retrofit imports: - mesa-panvk-bifrost/ — r1..r4 era phase docs (iter1..iter18) (libmali stub blobs at iter18/blob/ excluded — 109MB of RE artifacts replaced with a README pointer) - mesa-panvk-bifrost-video/ — sibling campaign phase docs + probe - evidence/ — frozen .tgz source snapshots at each milestone (basis for the 0005 patch diff generation) Future iterations should branch off here from day one, so each iter is a commit rather than a snapshot. See [[feedback-session-local-process-pins]] for the process drift this retrofit closes. Total: 1.9 MB across 124 files. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-23 05:25:37 +02:00
parent 430d0da278
commit a4e7d8ab90
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+iter8 Zink-on-PanVk-Bifrost RED finding — captured 2026-05-19 on ohm
+(PineTab2 v2.0, RK3566, Mali-G52 r1 MC1, Mesa 26.0.6, kernel 7.0.0-danctnix1-6)
+
+===== eglinfo with Zink + PanVk attempted =====
+$ sudo -u mfritsche XDG_RUNTIME_DIR=/run/user/1001 WAYLAND_DISPLAY=wayland-0 \
+  MESA_LOADER_DRIVER_OVERRIDE=zink PAN_I_WANT_A_BROKEN_VULKAN_DRIVER=1 eglinfo
+
+WARNING: panvk is not a conformant Vulkan implementation, testing use only.
+MESA: error: Zink requires the nullDescriptor feature of KHR/EXT robustness2.
+WARNING: panvk is not a conformant Vulkan implementation, testing use only.
+MESA: error: Zink requires the nullDescriptor feature of KHR/EXT robustness2.
+...
+OpenGL core profile vendor: Mesa
+OpenGL core profile renderer: llvmpipe (LLVM 22.1.3, 128 bits)        ← FALLBACK
+OpenGL core profile version: 4.5 (Core Profile) Mesa 26.0.6-arch1.1
+RC=0  (but Zink did NOT load — fell back to llvmpipe SW rasterizer)
+
+===== PanVk-Bifrost vulkaninfo confirms robustness2 NOT in extension list =====
+$ PAN_I_WANT_A_BROKEN_VULKAN_DRIVER=1 vulkaninfo | grep -iE "robust|nullDescriptor"
+
+VkPhysicalDevicePipelineRobustnessPropertiesEXT: present
+  defaultRobustnessStorageBuffers = ROBUST_BUFFER_ACCESS
+  defaultRobustnessUniformBuffers = ROBUST_BUFFER_ACCESS
+  defaultRobustnessVertexInputs   = ROBUST_BUFFER_ACCESS
+  defaultRobustnessImages         = ROBUST_IMAGE_ACCESS
+
+Device extensions present:
+  VK_EXT_image_robustness    (different extension)
+  VK_EXT_pipeline_robustness (different extension)
+
+VkPhysicalDeviceImageRobustnessFeaturesEXT.robustImageAccess = true
+VkPhysicalDevicePipelineRobustnessFeaturesEXT.pipelineRobustness = true
+
+NOT present:
+  VK_EXT_robustness2          ← what Zink wants
+  VK_KHR_robustness2          ← what Zink wants
+  VkPhysicalDeviceRobustness2FeaturesEXT.nullDescriptor
+
+===== Mesa source: the gate =====
+File: ~/src/mesa-ref/mesa/src/panfrost/vulkan/panvk_vX_physical_device.c
+
+  line  94:  .KHR_robustness2 = PAN_ARCH >= 10,
+  line 194:  .EXT_robustness2 = PAN_ARCH >= 10,
+  line 590:  .nullDescriptor  = PAN_ARCH >= 10,
+
+Bifrost is PAN_ARCH 6 (G31/G52/G72) or 7 (G52 r1/G76). Both fall OUTSIDE
+the `>= 10` gate. Mali-G52 r1 on ohm reports as PAN_ARCH=7 (per iter1 driver
+log: arch=7 in the panvk_physical_device.c switch statement).
+
+Valhall (PAN_ARCH=9), Bifrost, and the experimental v14 fifthgen are all
+denied robustness2 with the same hardcoded gate.
+
+===== Zink's hard requirement =====
+File: ~/src/mesa-ref/mesa/src/gallium/drivers/zink/zink_screen.c:3488-3489
+
+  if (!screen->info.rb2_feats.nullDescriptor) {
+     mesa_loge("Zink requires the nullDescriptor feature of KHR/EXT robustness2.");
+     ...
+  }
+
+No ZINK_DEBUG flag in zink_screen.c:97-127 disables this check. The feature
+is a hard prerequisite for Zink.
+
+===== NIR side: the feature already plumbs through =====
+File: ~/src/mesa-ref/mesa/src/panfrost/vulkan/panvk_vX_nir_lower_descriptors.c:1309
+  .null_descriptor_support = dev->vk.enabled_features.nullDescriptor,
+
+File: ~/src/mesa-ref/mesa/src/panfrost/vulkan/panvk_vX_shader.c:1355
+  .robust_descriptors = dev->vk.enabled_features.nullDescriptor,
+
+The NIR lowering code already reads `enabled_features.nullDescriptor` —
+i.e., the plumbing exists per-arch. The gate at line 590 is what blocks
+the feature from being *enableable* on Bifrost; the underlying lowering
+machinery is already there and would activate if the feature were exposed.
+
+That doesn't guarantee Bifrost's hardware can correctly handle a null
+descriptor read (the gate may exist *because* Bifrost can't), but iter4
+proved descriptor handling works for valid cases — and "null descriptor"
+mostly means "shader accesses an unbound binding cleanly without GPU fault."
+
+===== Bigger picture =====
+This is the campaign's first real finding. PanVk-Bifrost is functionally
+solid for everything iter1–7 tested, but Zink (and presumably many other
+Vulkan apps that opt into modern descriptor features) requires extensions
+that PanVk-Bifrost gates out.
+
+For the TuxRacer-via-Zink path, this MUST be fixed before iter9 makes sense.