NaCl loader for Linux arm64, armhf or amd64 depending on 32-bit support?

[illwieckz]

With box64 support having been implemented (useful for ppc64el and riscv64), I wonder if the arm64 build would be able to ship both armhf and amd64 NaCl loaders.

On a system without 32-bit support, like Asahi Linux, the amd64 nexe would be loaded running box64.
Otherwise the armhf loader will be loaded, for guaranteed native performance.

[illwieckz]

Running the amd64 loader on box64 may actually unlock the arm64 flatpak. Right now we don't provide any arm64 flatpak because the armhf loader doesn't run in flatpak for unknown reasons.

[slipher]

There's a precedent in the Windows 32-bit release shipping 32- and 64-bit NaCl runtimes. The 32-bit Windows binary checks if it is running on 64-bit Windows and chooses the 64-bit NaCl in that case. I guess this is mostly for convenience of devs testing the 32-bit Windows release without needing a real 32-bit Windows edition.

So similarly the arm64 binary could check for evidence of 32-bit binary support in the processor, kernel, and/or userspace, and select the armhf runtime in that case.

[illwieckz]

Yes that's what I think about.

[illwieckz]

We are on the edge of making NativeClient run everywhere. 😜️

OK, it's hacky, but still…