Building Firefox 32-bit On Linux 64-bit

Note

Unless you really want to target older hardware, you probably want to Build Firefox 64-bit since it is better-supported.

Before following these 32-bit-Firefox-specific instructions, follow the Building Firefox On Linux instructions to ensure that your machine can do a normal build.

Instructions for Ubuntu 19.10

These steps were verified to work as of June 2020.

Run rustup target install i686-unknown-linux-gnu to install the 32-bit Rust target.
Install 32-bit dependencies with the following command (this shouldn’t try to remove packages. If this is the case, those instructions won’t work as-is):

sudo apt install gcc-multilib g++-multilib \
  libgtk2.0-dev:i386 libgtk-3-dev:i386 libpango1.0-dev:i386 libxt-dev:i386 \
  libx11-xcb-dev:i386 libpulse-dev:i386 libdrm-dev:i386

Then, create a mozconfig file in your Firefox code directory (probably mozilla-unified) that looks like the following example:
```
ac_add_options --target=i686
```
Run ./mach build.