Firefox 70 on POWER

Firefox 70 is out and about. This is a very important release particularly for Power ISA because this includes a repaired 64-bit xpconnect and build system support for VMX and VSX (with VMX support in parts of the DOM and for libjpeg). VMX/VSX support is determined at runtime but I still advise if you build yourself to manually specify your CPU to the compiler (such as -mcpu=power9) to make sure everything is detected and better code can be generated. All these features work on both big and little endian configurations.

Fx70 is also the first release to officially enable the Quantum Render GPU-accelerated 2D compositor on all Windows-supported GPUs, which emerged from the Servo browser testbed as WebRender and has been gradually translated to Firefox. This is clearly the intended future of the browser, so we need to ensure it's operational on our platform.

AMD has been a supported GPU since Fx68 (Northern Islands, i.e., Radeon HD 6000 et al., and newer), so while Linux is not currently an officially supported Quantum Render target the WX 7100 sold with the Talos II should work. And, well, it does.

Performance is a bit sprightlier and I see better FPSes in demos, though our FPS rate is now increasingly JavaScript limited (yes, I know) as the rest of the rendering chain gets faster and faster. I have not encountered any stability or rendering issues with it so far. To enable WebRender, you need to enable hardware GPU acceleration in general and make sure that's working first; go to about:config, set layers.acceleration.force-enabled to true and restart the browser. I've been running with GPU acceleration myself for the past several releases, so I know it should work on at least the WX7100. Verify it's enabled by going to about:support and making sure that acceleration does not appear as "Blocked."

Once you have established GPU acceleration is enabled and operational, then go back to about:config, set gfx.webrender.all to true and restart the browser again. Go back to about:support; the window should look like the smaller one in the first screenshot. If sites go haywire, don't render right or seem to animate improperly, please flip those prefs back and compare so we can figure out why.

Northern Islands is a pretty low bar for WebRender and frankly if you're trying to run this on an even older AMD (or ATI??) GPU, you'll probably have lots of problems with almost certainly no benefit. Likewise, if you try to do this on Nvidia with nouveau, you're crazy. I don't see any reason why this wouldn't work on the *BSDs but I'd be interested to hear from anyone who has tried.

Meanwhile, more VMX and VSX improvements are in the pipeline and are certain to reach you faster with the increased release cadence in 2020. The .mozconfigs I personally use and support are unchanged from Firefox 67.


  1. It was finally in DNF today on Fedora 30, so I finally have it on my Blackbird. JS seems much faster on some things, but page load times are quite slow compared to 69 on others, though seem more responsive after loading. Overall liking it quite a bit.

  2. I'm using Falkon on my Librem 13 (not a Raptor-owner yet).

    If you are a freedom and security conscious computer user I find it odd if you use the stuff that comes from Mozilla directly. There is Iceweasel for those who think they need Gecko and Spidermonkey to surf the web.

    1. Since Mozilla doesn't issue builds for POWER9, strictly speaking nobody running it on OpenPOWER is using anything from them "directly."


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