Google has significantly advanced its efforts to have Android run on CPUs that use the RISC-V instruction set architecture.

A Monday post to the ads and search giant’s open-source blog opened with an explanation that Android “supports many different device types and CPU architectures” then added “We’re excited to be adding a new one to that list - RISC-V.”

The post, penned by Lars Bergstrom, a Googler with responsibility for Android platform programming languages, and Greg Simon who considers low-level operating systems, revisits Google’s November 2022 decision to start accepting Android patches for RISC-V.

“The latest update that we have is that now not only are we accepting patches, but we have begun to mature support for RISC-V in Android,” the pair wrote. “RISC-V is a modular ISA, meaning that there are a large number of optional extensions. We have also determined an initial set that we feel is critical to ensure that any CPU running RISC-V will have all of the features we expect to achieve high performance.”

The current set of patches support building and running a basic Android Open Source Project experience, the pair wrote. But “work on a fully optimized backend for the Android Runtime (ART) is still a work in progress.” So is plenty of other work.

But progress is clearly being made as Bergstrom and Simon wrote “Later this year, we expect to have the NDK ABI finalized and canary builds available on Android’s public CI soon and RISC-V on x86-64 & ARM64 available for easier testing of riscv64 Android applications on a host machine.”

By 2024, the pair expect to have emulators available publicly, “with a full feature set to test applications for various device form factors!”

Wearable devices will be the first targets, per last week’s news that Google and Qualcomm will bring the Android-adjacent Wear OS to RISC-V.

Bergstrom and Simon also advised coders to “stay tuned as we look into ways to make it as easy for Android developers writing native to target new platforms as it is for our Java and Kotlin developers!”

RISC-V is permissibly licensed, meaning chip designers are free to use the architecture but aren’t compelled to share their work as is required under other forms of open-source license. Interest in the ISA is high, as it offers the chance to create custom silicon without a requirement to pay royalties as is the case when customising Arm cores into finished products.

Open-source development’s ability to create and sustain digital public goods has become a key strategy for many tech stakeholders, often thanks to long and bitter experience of having their activities dictated by the owners of dominant platforms. Intel and Arm’s dominance of CPU architectures has gone unchallenged for decades.

Android on RISC-V is a threat to that dominance, because the global smartphone market’s billion-plus annual shipments alone are a huge market opportunity. So are the half a billion wearables already shipping each year.

Google’s extra push to have Android run on the ISA is therefore a potential harbinger of big change. But perhaps not rapid change, as RISC-V silicon that can go head-to-head with SoCs from the likes of Qualcomm don’t yet exist. But they’re clearly going to arrive in not too many years. ®

https://www.theregister.com//2023/10/31/google_android_risc_v/