Sigil crashes in UbutuStudio 26.04

[DiapDealer]

It might be difficult getting good Vulkan support with the nouveau drivers.

vkcube produces the spinning cube for me right out of the box. My Sigil debug info looks like this (with no env vars set):

Warning: GBM is not supported with the current configuration. Fallback to Vulkan rendering in Chromium.

Debug: 
Chromium GL Backend: angle
Chromium ANGLE Backend: default
Chromium Vulkan Backend: native

QSG RHI Backend: OpenGL
QSG RHI Backend Supported: yes
QSG RHI Device: NVIDIA Corporation NVIDIA GeForce GTX 1660 Ti/PCIe/SSE2 4.6.0 NVIDIA 595.71.05
QSG RHI GPU Vendor: Nvidia

Using GLX: yes
Using EGL: no
Using GBM: no
Using Shared GL: yes

Init Parameters:
 *  application-name sigil
 *  browser-subprocess-path /tmp/.mount_Sigil-pHCKiC/usr/libexec/QtWebEngineProcess
 *  disable-blink-features WebOTP
 *  disable-features EyeDropper,BackgroundFetch,InstalledApp,WebOTP,WebPayments,WebUSB,StandardCompliantNonSpecialSchemeURLParsing,AcceleratedVideoDecoder
 *  disable-gpu-memory-buffer-video-frames 
 *  disable-setuid-sandbox 
 *  disable-speech-api 
 *  enable-features NetworkServiceInProcess2,TracingServiceInProcess,Vulkan
 *  enable-logging 
 *  in-process-gpu 
 *  touch-events auto
 *  use-gl angle
 *  use-vulkan native

[47793:47836:0501/164307.422278:WARNING:viz_main_impl.cc(85)] VizNullHypothesis is disabled (not a warning)
Warning: Failed to register with host portal QDBusError("org.freedesktop.portal.Error.Failed", "Could not register app ID: Connection already associated with an application ID")
Debug: GPU Compositing: Enabled
Debug: ANGLE_OPENGL display is initialized:
  GL Renderer: ANGLE (NVIDIA Corporation, NVIDIA GeForce GTX 1660 Ti/PCIe/SSE2, OpenGL 4.5.0 NVIDIA 595.71.05)
  0 GPU(s) detected:
    Disabled
  NVIDIA Optimus: disabled
  AMD Switchable: disabled
Debug: Compositor Type: Native
Debug: QPA Platform Plugin: xcb
Debug: Skia Graphics Context Type: GaneshVulkan
Debug: Native Buffer Supported: no
Debug: Native Pixmap Support Type: None
Debug: Native Skia Output Device: OpenGL
Debug: Compositor Type: Native
Debug: QPA Platform Plugin: xcb
Debug: Skia Graphics Context Type: GaneshVulkan
Debug: Native Buffer Supported: no
Debug: Native Pixmap Support Type: None
Debug: Native Skia Output Device: OpenGL
Debug: Compositor Type: Native
Debug: QPA Platform Plugin: xcb
Debug: Skia Graphics Context Type: GaneshVulkan
Debug: Native Buffer Supported: no
Debug: Native Pixmap Support Type: None
Debug: Native Skia Output Device: OpenGL
Debug: Initializing buffer 0x7fc7e04c5e70 with SharedImage:
Debug:   Usage: DisplayRead|DisplayWrite
Debug:   Pixels size: 1056x944
Debug:   Format: RGBA_8888
Debug:   Backing: WrappedSkImage
Debug: VULKAN: Importing VkImage into GL Texture.
Debug: Initializing buffer 0x7fc7e0990a50 with SharedImage:
Debug:   Usage: DisplayRead|DisplayWrite
Debug:   Pixels size: 1056x944
Debug:   Format: RGBA_8888
Debug:   Backing: WrappedSkImage
Debug: VULKAN: Importing VkImage into GL Texture.
Debug: VULKAN: Importing VkImage into GL Texture.

My problem is that Sigil's Preview renders much, much faster when bypassing Vulkan using QT_QUICK_BACKEND=software. The debug output when that is set looks like:

Debug: 
Chromium GL Backend: disabled
Chromium ANGLE Backend: disabled
Chromium Vulkan Backend: disabled

QSG RHI Backend: OpenGL
QSG RHI Backend Supported: no
QSG RHI Device: NVIDIA Corporation NVIDIA GeForce GTX 1660 Ti/PCIe/SSE2 4.6.0 NVIDIA 595.71.05
QSG RHI GPU Vendor: Nvidia

Using GLX: yes
Using EGL: no
Using GBM: no
Using Shared GL: yes

Init Parameters:
 *  application-name sigil
 *  browser-subprocess-path /tmp/.mount_Sigil-pmkNai/usr/libexec/QtWebEngineProcess
 *  disable-blink-features WebOTP
 *  disable-features EyeDropper,BackgroundFetch,InstalledApp,WebOTP,WebPayments,WebUSB,StandardCompliantNonSpecialSchemeURLParsing,AcceleratedVideoDecoder
 *  disable-gpu 
 *  disable-gpu-memory-buffer-video-frames 
 *  disable-setuid-sandbox 
 *  disable-speech-api 
 *  enable-features NetworkServiceInProcess2,TracingServiceInProcess
 *  enable-logging 
 *  in-process-gpu 
 *  touch-events auto
 *  use-gl disabled

[57044:57080:0501/165504.391198:WARNING:viz_main_impl.cc(85)] VizNullHypothesis is disabled (not a warning)
Warning: Failed to register with host portal QDBusError("org.freedesktop.portal.Error.Failed", "Could not register app ID: Connection already associated with an application ID")
Debug: GPU Compositing: Disabled
Debug: ANGLE is disabled:
  GL Renderer: 
  Software Renderer: yes
  Primary GPU: Disabled

Debug: Compositor Type: Software
Debug: QPA Platform Plugin: xcb
Debug: Compositor Type: Software
Debug: QPA Platform Plugin: xcb
Debug: Compositor Type: Software
Debug: QPA Platform Plugin: xcb
Debug: Compositor Type: Software
Debug: QPA Platform Plugin: xcb
Debug: Compositor Type: Software
Debug: QPA Platform Plugin: xcb
Debug: Compositor Type: Software
Debug: QPA Platform Plugin: xcb

I have no idea why software rendering would be faster, but it is. Noticeably so.

[DiapDealer]

Originally Posted by philja

Just tried that. On UbuntuStudio, it's vkcube like on Kevin's machine. That command gets the spinning cube in a separate window. Looks good - neat demo.

That would indicate that you have everything needed for Vulkan support. Just not sure about Qt's Vulkan integration.

[philja]

Originally Posted by DiapDealer

I tend to assume that the video driver (or hardware) is aging or insufficient whenever QtWebEngine's hardware acceleration needs to be disabled for Sigil to work on Linux or Windows. But this was all working out of the box before @philja had upgraded some hardware (and reinstalled the OS) if I'm reading things correctly.

So unless the graphics card was somehow downgraded, I would expect things to work as they did. Especially since the version of Qt being used stayed the same--due to the AppImage being the same).

My graphics card is not new. Here's the 'other story' I referred to in an earlier post.

Back in the summer of 2022, when I updated the linux os from 20.04 LTS to 22.04.1 LTS, I had serious display problems. This was the first LTS after UbuntuStudio went to KDE Plasma from Xfce, iirc. The consensus at the time was that my graphics card was incompatible with Wayland. I have no serious demands on display graphics (no games, very little video work) so I just removed the graphics card to fall back onto the mobo on-board graphics. I also found a way to go back to X11 instead of Wayland.

My linux machine shares a 27" Iiyama screen, keyboard and trackball with the Windows 11 box via an hdmi KVM switch. That has worked impeccably for some years.

With the passing of time, I started getting some problems with the older linux hardware so I went for an upgrade to a new GigaByte B760M LGA1700 DDR4 Mobo with Intel i5 14600K processor and a new SSD disk. Sadly, I couldn't get the new linux box to light up the screen - not even the GigaByte splash screen, let alone into the BIOS.

So I took it back to the local hardware guy who demonstrated that the new box did start up ok. Back at home, I tried bypassing the KVM switch, interchanged the 3 hdmi cables, but couldn't find a way to get anything to display.

Back to the computer guy with my box and the 3 hdmi cables - and he couldn't get the splashscreen or bios to come up with any of my cables. He gave me a new hdmi cable which did work in his workshop.

Back home, the new hdmi cable and a direct connection (without the KVM) still failed to get the display going. Despair was certainly in the air. Then I had the idea to try putting a graphics card in to see if it gave a better hdmi signal. After searching in the archives, I found this old card, which had been removed in 2022 and I hoped that with the passing of time, Wayland would have learned to cope with it. We put it back in to test. Everything worked fine, and I booted up 26.04 LTS on a USB stick to test it before making a fresh install.

Normally, I wait until the LTS gets to the .1 release in early summer, but since 26.04 was released out of beta at the time my new box was ready, I went for that rather than an older version.

Why the new Gigabyte mobo couldn't drive my Iiyama screen via an hdmi connection with old or new cables whereas the much older mobo had no problem, remains a mystery.

[KevinH]

Do you still have the other graphics card installed or a motherboard based card?

The reason I ask is that QtWebEngine really can have problems when more than one graphics system exists on a system. To the extent that disabling the unwanted card in BIOS may be needed.

Perhaps that is what is causing the problems?

On some system with an integrated video system and a discrete gpu card that is nvidia it says you can forcibly select the nvidia gpu on Linux by typing:

Check current profile:
prime-select query

Switch to dedicated:
sudo prime-select nvidia

Switch to integrated:
sudo prime-select intel

Restart your application (or reboot) for changes to take effect.

[DNSB]

On my Ubuntu 26.04 install on a VMWare VM, vulkan is installed but vkcube not vkcube-wayland gets me the spinning cube.

david@Ubuntu-VM:~$ lspci -k | grep -A 3 "VGA"
00:0f.0 VGA compatible controller: VMware SVGA II Adapter
Subsystem: VMware SVGA II Adapter
Kernel driver in use: vmwgfx
Kernel modules: vmwgfx
00:10.0 SCSI storage controller: Broadcom / LSI 53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI (rev 01)
david@Ubuntu-VM:~$

Admittedly, the VMWare video drivers are about as vanilla as you can get.

[DiapDealer]

Pretty sure Google gave me a bum steer on vkcube-wayland.

[jugaor]

Maybe you’ve already considered this, and I just missed it, but if enabling GPU acceleration causes issues on various systems (and you say it doesn’t improve performance), wouldn’t it be better to leave it disabled by default in the AppImage and also in new installations on other OSs?

[DiapDealer]

Originally Posted by jugaor

Maybe you’ve already considered this, and I just missed it, but if enabling GPU acceleration causes issues on various systems (and you say it doesn’t improve performance), wouldn’t it be better to leave it disabled by default in the AppImage and also in new installations on other OSs?

That's not something we can accomplish without doing a bunch of reckless patching of QtWebEngine. Chrome's rendering process is complicated. We could set the environment variable to disable acceleration by default, but I'm not willing to do that. It works fine for people with newer hardware (and AMD gpu's on Linux). I'm not willing to unnecessarily diddle how Sigil's chrome renders for everyone. It's much safer to tell people to try turning it off whenever they run into trouble. Too many variables to try forcing the issue for everyone.