fix: ARM64 (aarch64) Linux build support - #3345
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Two fixes to allow ALVR to build natively on ARM64 Linux:
1. Fix char signedness in server_openvr (aarch64 uses unsigned char / u8)
- alvr/server_openvr/src/lib.rs: [0i8; 1024] -> [0u8; 1024] for
capture_frame_dir, which is a C char array. On ARM64 'char' is
unsigned by default, causing a type mismatch at compile time.
2. Document OpenVR ARM64 build requirement in build.rs
- OpenVR does not ship an ARM64 Linux prebuilt; added comment in
build.rs explaining how to build libopenvr_api.so from source.
3. Add wiki/Building-on-Linux-ARM64-(aarch64).md
- Step-by-step guide for building on aarch64 (tested on NVIDIA
DGX Spark / GB10 with Ubuntu 24.04 and CUDA/NVENC).
- FFmpeg NVENC encoders (h264/hevc/av1_nvenc) compile and work.
- alvr_dashboard and driver_alvr_server.so confirmed aarch64 ELF.
Tested-on: NVIDIA DGX Spark (GB10 / Blackwell), Ubuntu 24.04, aarch64
This was referenced Jul 31, 2026
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Summary
Fixes two issues that prevent ALVR from building natively on ARM64 Linux, and adds a wiki guide for aarch64 builds.
Tested on NVIDIA DGX Spark (GB10 / Blackwell, aarch64) running Ubuntu 24.04.
Fix 1: char signedness in
alvr_server_openvrOn ARM64, C
charis unsigned by default (u8), unlike x86-64 where it is signed (i8). This caused a compile-time type mismatch:Fix: Change
[0i8; 1024]→[0u8; 1024]. The existing.cast()on the pointer copy already handles both types correctly.Fix 2 + Docs: OpenVR ARM64 build requirement
OpenVR does not ship a prebuilt
libopenvr_api.sofor Linux ARM64. Added:build.rsexplaining how to build it from source (compiles in ~30s)Building-on-Linux-ARM64-(aarch64).mdBuild results on DGX Spark
bin/alvr_dashboardlib64/alvr/bin/linux64/driver_alvr_server.soNote: SteamVR does not run on ARM64 Linux, which limits streaming to non-SteamVR workflows. Happy to follow up with an issue/PR on standalone OpenXR server mode if that would be useful.