In 2018, a crack commando CPU was sent to an ASIC by a military court for a crime it didn't commit. This processor core promptly escaped from a maximum-security system-on-chip to the Los Angeles underground.
Today, still wanted by the government, it survives as a soldier of fortune. If you have a problem, if no one else can help, and if you can find it, maybe you can hire the A Team ... as in, the Arm Cortex-A5 Team.
Chip design house Arm today added the Cortex-A5 to its DesignStart program. That means startups, or larger businesses dabbling with making their own custom chips, can apply online for the CPU's blueprints, and after some paperwork and payment, get the materials needed to drop a set of A5s into their homegrown silicon.
The Cortex-A5, a modest little 32-bit Armv7 CPU introduced in 2009, can run Linux and its applications, as well as other operating systems and code, so the idea is you license the A5, pop it into your custom chip – which might, say, be a math accelerator or a controller for some larger equipment – and now you can run software and libraries tuned for Arm on it, making the design a little more flexible and capable.
Everyone's got a price
To get hold of this stuff, you need to pay Arm $75,000 upfront and $50,000 when you're finished and ready to tape-out – that's the industry jargon for sending the final design materials to whichever chip factory you're paying to manufacturer the component. To be clear, you still need to fork out for the fabrication and production of the chip yourself, which will not be cheap.
This $125,000 (roughly £96,000) gets you the Cortex-A5 CPU and a bunch of technology to wrap around it, plus a year of support from Arm engineers. If you want three years of support, pay more: $150,000 to start, $50,000 to finish.
If you start work on a custom chip using these designs, and then give up for whatever reason, you only pay the upfront $75,000 or $150,000 – the fifty large is coughed up when you're done and ready to tape-out. Also, this is on a per-project basis. If you want to design a followup or variant, and you want to use the A5 family again, you'll have to pay again.
Oh, and don't forget royalties. If you sell more than 1,000 chips using these DesignStart blueprints, you'll be expected to pay about three per cent of its ASP (average selling price) back to Arm. That royalty charge depends on how many Cortex-A5 cores you use: your custom chip can have one to four.
But, you say, Arm licenses CPU tech all the time: how is this approach any different to getting hold of the designs for, say, a Cortex-A9 or A72 or, heck, an A5 back in the day, by signing agreements, and paying money?
Well, we're told, DesignStart is supposed to be more streamlined. You fill out your details online, you're sent a non-negotiable licensing agreement, you sign and return that, set up payment, and you get the materials, all within a few days.
Free for every Reg reader – and everyone else, too: Arm Cortex-M CPUs for Xilinx FPGAsREAD MORE
That's a lot faster and easier than the usual dance you go through when working out a licensing agreement with Arm – mainly because companies aren't just buying chip designs, they're buying high-level support, tools, and any other necessary handholding.
If you just want to get started, well, that's why it's called DesignStart. Also, these DesignStart prices are cheaper than traditional A5 licensing agreements, we understand. Arm's trying to angle this as simplified, streamlined bargain, albeit for technology that's nearly 10 years old. On the other hand, it's "just" $125k or $200k, which will be dwarfed by all the other chip fabrication and final product production costs you'll rack up.
This Cortex-A5 core has been tried and tested in chips crafted by Samsung, AMD, Qualcomm, Atmel, Freescale, and others. It is not a top-performance part, coming in at 80 per cent the performance of the widely used Cortex-A9, and is more suitable as the glue between IO interfaces and dedicated silicon, such as machine-learning accelerators, or as a super-microcontroller for embedded applications and Internet-of-Things devices and gateways.
Bear in mind it does have a floating-point unit, and Arm's SIMD NEON engine, making it pretty capable for a small low-power silicon brain. Just one CPU core, minus all the extras, with 4KB of instruction cache, and 4KB of data cache, comes in at 0.28 mm2 of die area, and consumes about 100µW per MHz, at 40nm. It is scalable from 100MHz into GHz territory, if necessary.
When you get hold of the blueprints, you get thrown in a load of Arm tech to wrap around the cores: controllers for interrupts, memory, and second-level cache, peripherals including serial ports, timers, and a watchdog, a TrustZone environment, and a CoreLink NIC-400 interconnect to join the custom portions of the chip to the CPU cores.
All of this comes as open-source instruction set architecture RISC-V slowly and quietly stalks Arm.
The RISC-V Foundation – backed by big names like Google, Nvidia, Western Digital, Marvell, Samsung and Qualcomm – provides a freely available instruction set and related specifications that people can implement in FPGAs and system-on-chips. These implementations can be open source and free to use, making them potentially attractive to engineers looking for off-the-shelf technology to improve and drop into their custom accelerators. Alternatively, they could design their own RISC-V CPUs from scratch – there's a contest underway right now to encourage just that.
If you want to go down the RISC-V route, though, you still have to pay to fabricate the designs, which costs millions of dollars if you want to do it right. Startups like SiFive exist to take care of that for you, for a fee, of course. Then there's the usual costs of building a product around the chip.
This free, as in free speech, alternative is enough to put some pressure on Arm to ensure its paid-for proprietary processor designs remain competitive versus the free and open blueprints from the RISC-V world. As Arm CEO Simon Segars put it, RISC-V is keeping Arm "on its toes," and making it rethink some of its licensing.
Phil Burr, Arm's director of portfolio product management, told The Register the DesignStart program and it plans to include the Arm Cortex-A5 were started well before RISC-V began rising to greater attention. Indeed, DesignStart dates back to the late 2000s, although to our mind, has mainly offered Cortex-M-class materials.
Whatever you think of the timing, Arm has changed tack. It virtually never talks about licensing costs in public, and now it's setting out a stall with a price list hanging on it. Sure, the A5 is nearly 10 years old. However, it is comparable to freely available 32-bit RISC-V-compatible designs.
Your humble hack feels as though a line is being drawn in the sand. Arm appears to be saying: there are hidden costs to RISC-V, whereas we'll lay our hand on the table. $125,000, and that's our final offer. ®