Was thinking about the chatter on the X280 and went back an old article I posted begin of Jan.
Def appears a fit for our new platform.
Part snip below.
SiFive introduces a new high-performance coprocessor interface targeting custom accelerators; scores design wins from Google, NASA.
fuse.wikichip.org
Vector Coprocessor Interface Extension (VCIX)
At the 2022 AI Hardware Summit, Krste Asanovic SiFive Co-Founder and Chief Architect introduced a new Vector Coprocessor Interface Extension (VCIX).
As customer evaluation of the X280 went underway, SiFive say it started noticing new potential usage trends for the core. One such usage is not as the primary ML accelerator, but rather as a snappy side coprocessor/control processor with ML acceleration functionality. In other words, SiFive says it has noticed that companies were considering the X280 as a replacement coprocessor and control processor for their main SoC. Instead of rolling out their own sequencers and other controllers, the X280 proved a good potential replacement.
To assist customers with such applications, SiFive developed the new Vector Coprocessor Interface Extension (VCIX, pronounced “Vee-Six”). VCIX allows for tight coupling between the customer’s SoC/accelerator and the X280.
For example, consider a hardware AI startup with a novel way of processing neural networks or one that has designed a very large computational engine. Instead of designing a custom sequencer or control unit, they can simply use the X280 as a drop-in replacement. With VCIX, they are given direct connections to the X280. The interface includes direct access into the vector unit and memory units as well as the instruction stream, allowing an external circuit to utilize the vector pipeline as well as directly access the caches and vector register file.
The capabilities of essentially modifying the X280 core are far beyond anything you can get from someone like Arm. In theory, you could have an accelerator processing its own custom instructions by doing operations on its own side and sending various tasks to the X280 (as a standard RISC-V operation) or directly execute various operations on the X280 vector unit by going directly to that unit. Alternatively, the VCIX interface can work backward by allowing for custom execution engines to be connected to X280 for various custom applications (e.g., FFTs, image signal processing, Matrix operations). That engine would then operate as if they are part of the X280, operating in and out of the X280’s own vector register file. In other words, VCIX essentially allows you to much better customize the X280 core with custom instructions and custom operations on top of a fully working RISC-V core capable of booting full Linux and supporting virtualization.
