To be clear this is for cross-development (ie. Aarch64 bare-metal target on an x86_64 host).

I've downloaded the latest toolchain from ARM.

Extracting from the .tar.xz file results in bin, include, lib, libexec and share directories.

The files/directories in bin, include, lib/gcc and libexec have nice unique names and so fit in Slackware's /usr/bin, /usr/include, /usr/lib64 and /usr/libexec.

But what should I do about

The files in these directories share names with pre-existing ones for the normal x86_64 GNU toolchain.

Should I just put the whole lot in /usr/local?

You could put the files below /usr/local or you could place the files in some directory below /opt.

Instead of simply copying directory structures, you could also create a directory structure below a temporary directory and then from that temporary directory create a Slackware package with makepkg. Then you can install and later easily remove or upgrade your own custom Slackware package.

Another option to get a working ARM toolchain is to use the Slackware sources for the llvm package, modify the build script to add the targets that you want to the line:

...or simply remove that line to instead as default, build all supported cross compilers including ARM.

After running that script (as root) you have your own custom llvm package with support for cross compiling which you can use to replace the original llvm package.

regards Henrik

Stuff like this I usually put in /opt/. That's safe and makes sense. In the future, maybe that install will have a file that conflicts with your system files.

Thanks all!

I've put everything in /usr/local.

That way all the new bin, include, lib etc. things are already findable via $PATH etc.