1301011 - Scrolling artifacts on pages with non-scrolling parts on llvmpipe

Status: RESOLVED INCOMPLETE

(Core :: Graphics: Layers, defect, P3)

Description

[Henri Sivonen (:hsivonen)]

Attachment: Screenshot

Steps to reproduce:
 1) Navigate to a long Discourse discussion, such as https://internals.rust-lang.org/t/need-help-with-emscripten-port/3154/100
 2) Log in.
 3) Click the "Reply" button to show the reply UI
 4) Scroll the discussion.

Actual results:
The view port becomes a mess of ill-positioned rectangular fragments of the page.

Expected results:
Expected the discussion to scroll cleanly with the top bar and the bottom reply area staying intact.

Additional info:
Also occurs on Twitter, but the Discourse reply UI makes the problem particularly bad.

Graphics info (Ubuntu 16.04 on VirtualBox without host OpenGL passthrough):
Features
Compositing	Basic
Asynchronous Pan/Zoom	none
WebGL Renderer	VMware, Inc. -- Gallium 0.4 on llvmpipe (LLVM 3.8, 128 bits)
WebGL2 Renderer	VMware, Inc. -- Gallium 0.4 on llvmpipe (LLVM 3.8, 128 bits)
Hardware H264 Decoding	No
Audio Backend	pulse
GPU #1
Active	Yes
Description	VMware, Inc. -- Gallium 0.4 on llvmpipe (LLVM 3.8, 128 bits)
Vendor ID	VMware, Inc.
Device ID	Gallium 0.4 on llvmpipe (LLVM 3.8, 128 bits)
Driver Version	3.0 Mesa 11.2.0
Diagnostics
AzureCanvasAccelerated	0
AzureCanvasBackend	skia
AzureContentBackend	skia
AzureFallbackCanvasBackend	none
CairoUseXRender	0
Decision Log
OPENGL_COMPOSITING	
Blocklisted; failure code BLOCKLIST_FEATURE_FAILURE_SOFTWARE_GL

Comment 1

[Mason Chang [Inactive] [:mchang]]

Can you reproduce this on actual hardware?

Comment 2

[Henri Sivonen (:hsivonen)]

This isn't in VMWare. The GL driver is llvmpipe, whose vendor string happens to contain the name of "VMWare, Inc.", because they developed Gallium 3D.

I don't have any on-hardware Ubuntu installation where llvmpipe would get used naturally due to a lack of HW-backed GL drivers, and I'm shy to break any on my on-hardware installations to simulate the situation. So no, I don't have an on-hardware llvmpipe setup to test with. Sorry.

I'll try to see if I can repro with Intel's or Nvidia's HW-backed GL drivers.