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Background and Contributors
The post was written by Lars Bergstrom, who is responsible for programming language infrastructure on the Android platform, and Greg Simon, who handles low-level operating system work. They reviewed Google's decision, announced in November 2022, to accept RISC-V patches for Android.
Current Status
The update indicates that Android maintainers are no longer only accepting patches but have begun to provide mature support for RISC-V within Android. Because RISC-V is a modular ISA with many optional extensions, the Android team identified an initial set of required features that they consider essential for achieving the expected performance on RISC-V CPUs. That set includes the rva22 profile as well as the vector and vector cryptography extensions.
The current patchset supports building and running a basic Android Open Source Project experience. Work remains, including development of a fully optimized backend for the Android Runtime (ART) and additional optimization across AOSP, external projects, and compilers so they can generate code that leverages the latest approved RISC-V extensions.
Short-Term Roadmap
Later this year, the team expects the NDK ABI to be finalized. Canary builds will soon be available on Android's public continuous integration, and tools to enable easier host-side testing of riscv64 Android apps from x86-64 and ARM64 hosts are planned. A simulator with a full feature set for testing apps across various device form factors is expected to be made publicly available in 2024.
Google and Qualcomm have previously announced plans to bring the Wear OS platform to RISC-V, with wearables targeted as an initial device class.
Developer Guidance
The post encourages developers to follow progress as work continues to make it as straightforward for native code authors to target the new platform as it is for Java and Kotlin developers.
RISC-V Ecosystem and Strategic Context
RISC-V is an open, licensed ISA that allows chip designers to implement the architecture without the royalty model associated with some proprietary cores. Its adoption has grown from embedded and microcontroller domains into accelerators, servers, and mobile computing. Open hardware development has become strategically important across the industry, and RISC-V-based Android presents a potential challenge to longstanding CPU architecture incumbents, given the large annual market for smartphones and hundreds of millions of shipped wearable devices.
Collaboration and Standards Work
Supporting RISC-V in Android involves broad contributions across toolchains and supporting libraries. The Android effort is coordinated with community initiatives and with the RISE project, which aims to accelerate the availability of software for high-performance, energy-efficient RISC-V cores running advanced operating systems such as Android and Linux. RISE project members include several processor and IP vendors, silicon companies, and software contributors.
Build and Test Notes
It is already possible to build, test, and run Android support for RISC-V locally using AOSP targets and Cuttlefish virtual devices. Example commands shown by the Android team are:
$ lunch aosp_cf_riscv64_phone-userdebug $ m -j $ launch_cvd -cpus=8 -memory_mb=8192
After launching the virtual device, a VNC viewer can be used to connect and interact with the running device.
