What's Arctic Tern good for, anyway?

Date: 2022-08-21T20:19:00-07:00

Location: www.talospace.com

Arctic Tern (and its associated soft-BMC Kestrel) is a product that's hard to describe just looking at it. Is it a boot accelerator? Is it a BMC replacement? Is it a development board? Is it OpenPOWER's answer to the Pi Nano? (Answers to pop quiz: yes (in the sense you get the BMC up quicker), yes, yes, and sort of but not really, since the clock speed is too low and it lacks some accoutrements.)

Raptor's new manual should address some of these concerns, and particularly covers the worry I and others had about bricking our system trying to get it installed (disclosure: yours truly reviewed a pre-release copy and submitted comments). Yes, it does need a PCIe slot if you want it to act as a VGA controller or USB host device; yes, it comes with all the necessary cables, including a JTAG programmer; yes, it's compatible with the Blackbird; no, soldering isn't required. But the instructions that are there are step by step and copiously decorated with illustrative photographs such that anyone reasonably handy with their machine should be able to do it.

Instead, the biggest roadblock to the casual interest will likely be the programming: you have to build the FPGA bitstream and firmware image yourself, and then flash your unit manually. The modules don't come preconfigured. (What, did you think that JTAG box was included just for giggles?) Raptor provides Kestrel source and instructions for Debian Linux on an OpenPOWER host in the manual, but the instructions are lengthy, and there is no public build or any other binaries presently available. This is primarily due to the rapid background development but also consider it a minimum "hacker" threshold required to join the club. Other operating systems on Raptor or OpenPOWER hosts should work, but x86_64 users will have to bring up their own toolchains. Raptor did say that at some point there will be "known good" images, though when that will be is an open question since the Kestrel source isn't even close to stable right now. Compared to that, the requirement that you also patch the on-board BMC to disable it in software seems comparatively minor (and it's reversible).

So who's this good for? Raptor may have their own ideas about that, but from over here typing this on my (now switched over to KDE) Talos II, right now I see this product really for someone who wants all the pieces in one place to play with Microwatt to develop their own embedded applications for it. If you're one of those people, you may not even care about the state of Kestrel anyway; to you it would be merely an example. On the other hand, for those of us looking forward to a fully auditable BMC, Kestrel seems to be working but it may not be sufficient (or sufficiently solid) to replace your BMC today and you'd have to jump through a lot of hoops to do it. If that's all you're interested in, you may want to wait. But it comes with everything you need to get started and for those in its apparent target audience, the barriers to entry don't seem unreasonable.