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Firefox 94 comes with EGL on X11
Firefox 94 is coming out next week and brings awesome news. OpenGL EGL backend its enabled by default on Intel/AMD and recent Mesa for users on X11.
This project has been driven by Robert Mader (most of the EGL work), Andrew Osmond (glxtest fixes and config), Jamie Nicol (EGL/Android and partial damage), Greg V (partial damage support) and Jan Ikenmeyer (Darkspirit) (help with issues, testing).
Historically Linux comes with GLX (OpenGL X11 extension) but that era is finally ending and we’re moving forward to EGL which promises all the goodness you can expect from modern graphics subsystem…or you can create a texture over graphics memory at least 🙂
I’ll keep aside all EGL / GLX difference and focus to changes from user perspective. GLX is old, well debugged and tied closely to X11 which means seamless experience and wide support by gfx drivers (like proprietary NVIDIA ones). It’s used by most X11 applications and ‘just works’.
EGL is ‘new’ from Linux desktop perspective and used mainly by Wayland, Android and various small devices. It’s not fully supported by all desktop drivers and has glitches (broken rendering of transparent windows for instance). But as Wayland is gaining momentum also EGL is getting more attention and fixes on Linux desktop.
And why we actually want EGL? Because it gives us a cool toy – EGLImages (and EGLFence). EGLImage is an object which is created over a piece of GPU memory (which can be DMA-Buf), shared with different process, used as a frame buffer (target of GL rendering) or a texture (source of GL rendering).
EGLImage allows to use GPU memory in a very creative way. VA-API decoded video frames or WebGL scenes can be mapped as EGLImages, moved from decode process to rendering process and used as a texture. EGLFence allows to lock EGLImages across process so we don’t re-paint WebGL scene while it’s used in a different process or recycle VA-API video frames too early.
And what you can expect from EGL in Firefox? Faster WebGL rendering (used on Google Maps for instance), more effective rendering due to to partial damage support and potential VA-API video decoding (that’s blocked by Bug 1698778 on both Wayland and X11). It also unifies rendering path for Wayland and X11, which means X11 will gain features done for Wayland (suspended rendering for invisible windows, better VSync support and more).
NVIDIA is also working on EGL & DMA-Buf support in their proprietary drivers so there’s a hope for owners of such FOSS unfriendly hardware.
So give Firefox 94 a try. If anything goes wrong, please file a bug. You can also disable EGL and switch back to GLX. Go to about:config page and flip gfx.x11-egl.force-disabled preference and restart browser.
Firefox Wayland development in 2021
It’s been long time from my last update about Firefox news on Linux and I’ve finally got some time to sum up what we’ve been working on for last year and what’s coming. There haven’t been introduced any new exciting features (from Linux perspective) for the last year but rather a hidden but important changes.
From Linux desktop developers perspective 2021 is a year of Wayland. KDE has been shipping decent Wayland compositor which becomes default for Fedora 34. It’s actually pretty fast and gives you smooth feeling of “good old times” with X11/Gtk2/name-your-favorite environment where any graphics change was just instant without lags or slow transitions. I must mention Robert Mader who created a new Firefox Wayland SW backend for the KDE.
As major desktop distro (Ubuntu) is slowly moving to Wayland we’re getting more and more Wayland/Firefox users. Even notorious troublemaker (NVIDIA) decided to step in and support it.
What’s done for next releases?
It’s good that Wayland market share is rising but we also need to make sure that Firefox is ready to run there without any major issues and matches its X11 variant. There are two major areas where Firefox is behind its X11 counterpart – clipboard and popup handling. It’s given by some Wayland protocol features where we can’t simply duplicate the X11 code here.
Clipboard on Wayland is similar to X11 one but we need to translate Wayland asynchronous clipboard to Firefox/Web synced one. I tried various approaches but the best one seems to be just use the asynchronous Wayland clipboard as is and implement some kind of abstraction over it. That was implemented in Firefox 93 an it’s going to be shipped by default in Firefox 94.
On the other hand popups are the most annoying thing we have to implement on Wayland. Firefox just expect any popup can be created any time without its parent (or use main window as a parent) but Wayland requests strict popup hierarchy. It means every window can have only one child popup. When more than one popup is opened it has to be attached to the previously opened popup which becomes a parent for it. And when any popup in the chain is closed the popups must be rearranged to keep the chain connected. This involves all kind of popups like content menus, tooltips, extensions popups, permissions popups and so on. Plus there are some interesting bugs in Wayland protocol or Gtk so excitement/frustration is guaranteed and basic popup implementation becomes extraordinary challenge where small changes can introduce various regressions. Despite the ‘fun with popups’ the popup tracker is almost clear and we’ll ship it in Firefox 94.
One of main Wayland feature is support of monitors with various DPI/scale factor together. Fedora default compositor Mutter shows here a creative approach and reports screen sizes differently than other compositors. As we really want to know screen sizes Firefox tracks monitor changes from Wayland directly and find correct screen by matching screen left top corner point – which fortunately stays stays same for all compositor. We also stop painting Firefox window when screen scale changes so you should enjoy seamless experience on systems with various screen sizes with Firefox 93.
Future plans for Firefox 95
Firefox 95 development cycle begins next ween and I’m going to look to drag and drop which has been partially broken for long long time. Some Wayland specific fixes are already in Firefox 94 but we need to rework some parts to correctly copy files from remote destinations (like inbox) to local filesystems, fix names of dropped files or do tab preview of moved tabs. There are also new interesting compositors bugs as usually 🙂
Future plans for Firefox 96
Firefox Wayland port is generally done and there isn’t any big difference between X11 and Wayland variant at least on GNOME which Fedora uses as default environment. We’re fixing minor bugs and keep eye on user reports.
For next quarter I’d like to look at GPU process for Wayland. GPU process is running tasks related to graphics hardware and shields browser from HW drivers crashes. It’s also place where VAAPI video decoding should be run and will be properly sandboxed there (right now VAAPI is run in content process along general Firefox code, it’s restricted by content sanbox which leads to various VAAPI code crashes and failures).
Firefox – we’re finally getting HW acceleration on Linux
Firefox 84.0 is a big milestone for Firefox Linux development as it comes with HW acceleration by default for some Linux users. Stock Mozilla Firefox 84.0 enables WebRender (HW accelerated backend) for Gnome/X.org and Gnome/Wayland will be supported in Firefox 85.0. Fedora is bit ahead and enables WebRender for Gnome/Wayland in Firefox 84.0 too.
WebRender by default is restricted to AMD/Intel graphics cards as NVIDIA is known for various issues – both proprietary and Noveau drivers.
And why it’s enabled in Gnome only for now? For instance KDE is also a popular desktop environment. I think it’s because Gnome utilizes HW acceleration so when Gnome works on your box there’s assumption that Firefox will work too. KDE provides choices how to disable/restrict HW acceleration setup (for instance it supports disabled screen compositing) and it’s more difficult to cover various scenarios.
Another excluded group are XWayland users. It means you have Wayland as a desktop compositor but for some reasons you use X11 emulation layer and run Firefox as X11 application. It’s a valid scenario, Firefox with Wayland backend still suffers from some annoying bug, mostly related to popup windows.
But don’t worry, Mozilla folks are going to bring WebRender to the most Linux users on various desktops and graphics. Jan created a brief Linux WebRender state overview. And you can help with it! Please check if you have WebRender enabled and eventually try to enable it. Test various web pages, video playback, WebGL and report your experience. You can use comments below or drop me a mail at stransky@redhat.com.
The first fully tested Fedora Firefox package
We hit a big milestone in Firefox deployment on Fedora with firefox-84.0.2 package. It’s the first fully tested Firefox package released to Fedora users. Let’s see what’s so exciting on it.
Mozilla has a large testsuite as a part of development and release process. When any new patch hits Firefox repository, it’s built and tested for functional and speed regressions. The testsuite is also a developers nightmare as it contains some old and outdated test environments and it may be difficult to pass patches through it.
So if you download a Mozilla Firefox binary you can be sure it’s generally working at least on X.org and Ubuntu 18.04 which is main test setup there. But what about distro builds?
There are may differences how Firefox is built by various distributions. The very first difference is used compiler. Mozilla compiles by custom patched Clang which is not available for distributions although they actually don’t want it.
GCC is the favorite compiler among Linux hackers and that brings extra maintenance burden to Firefox distro maintainers. Compiler crashes and code miscompilation are companions of every new GCC version (no to mention an extra fun with LTO).
Distros also tend to modify Firefox sources with various integration patches or patches from Nightly, run Firefox on Wayland backend or use system NSS so maintaining such package is like dancing in a minefield.
And there comes the Mozilla testsuite. If we manage to run it in our environment with our package modifications it greatly helps to reduce unwelcome surprises like Bug 1893474. And it needs to run in automated manner and test every Firefox build we may release to user on all arches.
And that’s done now. Almost. The latest Firefox Fedora builds (F32, F33) run the testsuite as a part of the build process and test results are generated as a new package (firefox-testresults).
If I say we’re almost there, I mean the most difficult work is done as the tests are run in Koji. There are still some failing tests which needs to be inspected and disabled or fixed. The testsuite needs to be run on Wayland – it checks X11 backend now. And it should be integrated to Fedora test infrastructure to show test results in some user-friendly way.
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