And what stopped you to open a new thread on the Slackware - ARM sub-forum and to post your question about how to build the Firefox without PulseAudio on a ARM 64bit device?

https://www.linuxquestions.org/quest...kware-arm-108/

Doing like this would had the advantage that your question would have attracted the attention of more people who uses Slackware ARM and certainly they have more experience with this kind of devices. And Dr. Mozes, the lead developer of ARM port, is a quite friendly person.

Honestly, also myself I do not think that resurrecting the old threads is a good idea and I seen this kind of attitude on many forums.

Look what you did here: half of thread is about building a 3 years old Firefox on a 3 years old x86 system and other half is about building a latest Firefox of March, 2021 on an ARM 64bit device.

I hope that you agree that that could be quite confusing, specialy for a novice who search like you for "firefox pulseaudio alsa" in future.

I use a Pinebook Pro https://www.pine64.org/pinebook-pro/ with Debian and mostly I hang out in their forums. Which mostly deal with hardware issues. But a link to linuxquestions.org came up in a search and I hadn't been here in a year or so, so I looked up my password and logged in.

Not really much has changed, I first built Firefox 2-3 years ago on a Rock64. I've tried several times on a Raspberry Pi 3B but even with lots of swap space it can't quite do it. You really need 4 GB of RAM (plus 10 GB of swap). The architecture doesn't matter that much, the build process can tell what it's running on and adjust. It's simpler than building a kernel, less choices to make. Roughly as demanding of compile time, issues with overheating so you run about half the max number of compile jobs. And you can get away from the ESR (Extended Service Release) old Firefox versions but I did have to build a current Rust. Running Debian Bullseye so only the Rust was too old. It's the same process, only the machines have changed. The choices you make in your mozconfig mostly have to do with where to put stuff, are you using llvm or gcc, what python version, do you want pulseaudio or alsa or both enabled.