Box64 support on Linux Arm64

[illwieckz]

I have a local branch that attempts to detect if armhf hardware support is present on linux-arm64, and if yes, it uses the armhf loader, if not, it uses the amd64 loader on box64.

The code path to use one or the other works (except I haven't test on hardware with 32-bit that it actually detects the missing support), on my system supporting 32-bit it says the support is there and it uses the armhf loader.

I added a cvar to force the disablement armhf multiarch and then it uses the amd64 loader on box64 as expected.

I started implementing the bundling of box64 in external_deps too.

So the whole thing is almost there.

Anyway, whatever the loader, I get different errors with the NativeClient code, that may be related to Saigo (I used self-built loader and self-built Saigo compiler):

• armhf:

Unvanquished 0.56.2 Linux arm64 (GCC_10.2.1:aarch64-linux-gnu-g++) Jul  3 2026
…
Using loader args:  nacl_helper_bootstrap-ldarmhf nacl_loader-armhf --r_debug=0xXXXXXXXXXXXXXXXX --reserved_at_zero=0xXXXXXXXXXXXXXXXX -Q -v -B irt_core-armhf.nexe -e -i 100:18 -- cgame-armhf.nexe 100 
…
Loaded cgame VM module in 270 msec 
cgame NaCl armhf (Saigo_21.0.0/Clang_21.0.0:arm-nacl-clang++) Jul  3 2026 
Loading Lua plugin using a new Lua state. 
Wrote crash dump to crashdump/crash-nacl-CGame-1783087446249.dmp 
Warn: Error during initialization: CGame VM: Crashed with NaCl exception 

• amd64:

Unvanquished 0.56.2 Linux arm64 (GCC_10.2.1:aarch64-linux-gnu-g++) Jul  3 2026
…
Using loader args:  box64 nacl_loader-amd64 -Q -v -B irt_core-amd64.nexe -e -i 100:18 -- cgame-amd64.nexe 100 
…
Loaded cgame VM module in 5906 msec 
cgame NaCl amd64 (Saigo_21.0.0/Clang_21.0.0:x86_64-nacl-clang++) Jul  3 2026 
Loading Lua plugin using a new Lua state. 
Loaded font face 'unifont' [regular] from 'fonts/unifont.ttf'. 
Loaded font face 'Roboto' [bold] from 'fonts/Roboto-Bold.ttf'. 
Loaded font face 'Roboto' [italic, bold] from 'fonts/Roboto-BoldItalic.ttf'. 
Loaded font face 'Roboto' [italic] from 'fonts/Roboto-Italic.ttf'. 
Loaded font face 'Roboto' [regular] from 'fonts/Roboto-Regular.ttf'. 
Loaded font face 'FontAwesome' [regular] from 'fonts/fontawesome-webfont.ttf'. 
Loaded font face 'DejaVu Sans' [regular] from 'fonts/DejaVuSansCondensed.ttf'. 
Loaded font face 'Material Icons' [regular] from 'fonts/MaterialIcons-Regular.ttf'. 
Warn: Unable to open file }. 
Warn: Unable to open file {. 
Warn: Error during initialization: IPC: Timed out while waiting for VM message 

Actually that parsing error isn't new, maybe we got them with the armhf build before. It would be funny that amd64 on arm64 would produce similar bugs as armhf.

[illwieckz]

Loaded cgame VM module in 5906 msec

Also, we can see that loading the loader over box64 can be very slow, so we better increase vm.timeout which is currently set to 2 by default (that is too small!).