Support for RISC-V was dropped from Android's Generic Kernel Image (GKI) thanks to a patch successfully merged today.

The patch, filed under the topic "ack_riscv64_turndown" on the Android Open Source Project (AOSP) tracker, removes files from the Android Generic Kernel (GKI) that existed to implement support for RISC-V, an open CPU architecture that sees use in many kinds of electronics, though hasn't made the leap to smartphones yet.

"Remove ACK's [Android Common Kernel] support for riscv64. Support for risc64 GKI kernels is discontinued," the patch note briefly says. The deletion was submitted by a Google engineer, and naturally passed the review process.

It's a significant U-turn for the Chocolate Factory, which has accepted RISC-V patches for Linux-powered Android since November 2022 (including GKI patches), and formally added support in October 2023.

The practical effect of this is that Android operating system implementations using the next release of GKI won't work on RISC-V chips out of the box.

Support for RISC-V will have to be added back in by other developers, and while it's not unusual for SoC manufacturers and OEMs to make their own tweaks to Android, adding in support for a whole architecture is unusual.

It's unclear what kind of effect this will have on RISC-V's integration into the Android ecosystem. There are no RISC-V smartphones out there yet, so it won't make life hard for phone makers, but it's hard to see GKI support being axed as conducive for the adoption of the open source CPU arch. Android still accepts RISC-V patches via AOSP.

Google assures, however, that the end of RISC-V's GKI support isn't a death sentence for RISC-V on Android. "Android will continue to support RISC-V," the ad biz said in a statement to Android Authority. "Due to the rapid rate of iteration, we are not ready to provide a single supported image for all vendors."

To us, this sounds like Google thinks it's worth plowing on with RISC-V support in Android but doesn't think it's ready yet for prime time.

It's an especially weird time to make this kind of move since Qualcomm is set to incorporate RISC-V CPUs and Google's Wear OS for future wearables. The work of adding RISC-V support for Wear OS would surely carry over at least partially to Android. We've asked Google for further comment on its motivations for removing RISC-V support in GKI, and we'll update if we get a reply.

Meanwhile, the RISC-V community has issued its RISC-V Boot and Runtime Services Specification, which aims to define a common, generic platform on which OSes and hypervisors can start and manage a system. ®

https://www.theregister.com//2024/05/01/riscv_support_android_pulled/