[ilyt]

Only benefit is companies not having to pay ARM. The architecture NEVER WAS A PROBLEM for open, it was always the binary blobs required to run IP blocks put on the die with the cores that stopped people from using them.

ISA is the easy part. Even if you need to RE it, you only need to do it once.

Now hopefully with RISC V companies will be even more inclined to just upstream their drivers from the start (and not do the abominations that happen way too often on ARM side), but the ISA never was a problem for that.

[giantrobot]

> it was always the binary blobs required to run IP blocks put on the die with the cores that stopped people from using them

That's not going to change with RISC-V. If you've got silicon that has to conform with FCC regulations it's going to have non-modifiable firmware. No matter how open the rest of the system is, your WiFi and Bluetooth (and any other radios) will have closed firmware.

[drmpeg]

Probably a better example than WiFi would be the on-chip SDRAM controller. It's always somebody else's IP and there's a blob in the boot firmware that's just binary register settings. Like so:

https://github.com/u-boot/u-boot/blob/master/arch/riscv/dts/...

[leonheld]

I'm not from the US so not really familiar with FCC regulations.

> If you've got silicon that has to conform with FCC regulations it's going to have non-modifiable firmware.

Can you explain 'why?' or maybe throw me a link or two? Thanks!

[giantrobot]

The why is simple: Power/frequency limits allow everybody to be able to use personal consumer devices without licensing and without preventing other people from using their devices. If you modified your WiFi to blast out a 10W signal across multiple channels at your house, you completely ruin my ability to use Wifi at my house next door. Radio spectrum is shared by everybody.

As for reading there's CFR title 47 [0]. Parts 15 and 18 are germane for unlicensed radios and electronic devices. Parts 22 and 24 cover cellular devices.

The regulations don't explicitly say anything about firmware but to build devices that follow the regulations end user modifiable firmware is an implicit restriction. Even user serviceable antennas are restricted because radio device licenses cover not just the electrical output but total gain of the shipped antenna.

[0] https://www.ecfr.gov/current/title-47

[AnthonyMouse]

> The why is simple: Power/frequency limits allow everybody to be able to use personal consumer devices without licensing and without preventing other people from using their devices.

That explains why there are power/frequency limits, not why the device manufacturer should be deputized into responsibility for a sophisticated user's non-compliant device modifications.

Anyone can make an arc gap transmitter for morse code out of $3 in bits from any hardware store that will interfere with anybody else's radio devices in the vicinity. Anyone can buy ham radio equipment or built it from parts and do all kinds of non-compliant things with it. Then the FCC comes after you, not the hardware store or the device OEM.

Or more likely in the case of a WiFi device, comes after the person distributing custom firmware that purposely exposes a simple knob to allow unsophisticated users to exceed regulatory limits.

And if DD-WRT did that, they should expect a visit from The Government. But what should that have anything to do with Linksys or Netgear?

There aren't enough end users who know how to modify the firmware code themselves to matter, even if you make that "easy."

[giantrobot]

> There aren't enough end users who know how to modify the firmware code themselves to matter, even if you make that "easy."

This is just a silly statement. Go to an apartment complex sometime and browse the available WiFi networks. You'll see a huge number of them because everyone has the output power on their router set to the max value. There's plenty of places the 2.4GHz band is simply unusable because the noise floor is so high from a hundred base stations blasting out at full power.

If WifiBoost.exe could in tease that output power enough people would do it that WiFi or Bluetooth in some places would be completely unusable.

Modern radio basebands are largely software defined. The modulation/keying, power output, and transmitted bands are all defined in software. In order to sell that silicon as a Part 15 compliant device to end users the firmware needs to be locked. It's the digital equivalent of a fixed function radio. A manufacturer of a fixed function radio couldn't get a Part 15 license if it had a potentiometer on the back allowing you to dial up the output power, even if that potentiometer was locked under the case most people wouldn't open.

With an SDR the hardware plus software is considered the "device" for licensing purposes. If it supported unlocked or modifiable firmware it couldn't be easily/at all sold as a Part 15 device. It would be a different class of device and would require the end user to have a license to operate it.

[AnthonyMouse]

> You'll see a huge number of them because everyone has the output power on their router set to the max value.

None of these people are firmware developers. They used the setting that existed from the factory in their router or in something they downloaded from the internet, and in the vast majority of cases it wasn't even the second one.

> If WifiBoost.exe could in tease that output power enough people would do it that WiFi or Bluetooth in some places would be completely unusable.

Then WifiBoost.exe would be illegal and the developers would be subject to penalties.

It would also be ineffective, because you can't remove interference by increasing power. The "highest allowable power" setting is often the default because it gives the best range, and the purpose of allowing it to be set at all is so that the user can reduce interference at the expense of range by lowering the power level so fewer devices are overlapping.

It's hard to get people to avoid doing illegal things when breaking the law benefits them. It's not that hard when breaking the law is pointless and maladaptive regardless of whether or not they get caught.

It's notable that there have existed routers with completely open firmware and there is no epidemic of ordinary users installing shady firmware on them to violate regulatory limits. There is likewise full software defined radio hardware on the market, for which a license is required to transmit but not to buy it. Applying a different standard to consumer hardware which is available to exactly the same set of people makes no sense.

> With an SDR the hardware plus software is considered the "device" for licensing purposes. If it supported unlocked or modifiable firmware it couldn't be easily/at all sold as a Part 15 device. It would be a different class of device and would require the end user to have a license to operate it.

I'm not arguing about what the law currently is but rather about what it ought to be.

But I also think your analogy is flawed. If the manufacturer sells a device with a potentiometer whose maximum setting was within the regulatory range, or with a fixed power output, and then the user modifies the device to install one that can increase the power output, that should be on the user. So why is it different if the user modifies the device to install firmware that increases the power output?

You're essentially arguing not that the device can't include a potentiometer, but that the case has to be sealed so the user can't install one.

Which in turn prevents the user or any other third party from repairing the device or supporting it past when the vendor stops caring about it, inducing widespread security vulnerabilities as users commonly continue to use operational devices even after the hardware vendor stops issuing updates.

[Pet_Ant]

I think it is because the firmware guarantees that the radio behaves according to specifications. Much like the governor on a car.

[megous]

Can you explain wifi chips like rtl8852 that have power levels and channels specified in the linux drivers and are fcc certified, then?

[giantrobot]

It only has power level control up to the limits for ISM devices on its operating frequencies. Its license is only valid for antennas with specific gain.

You technically can overwrite its firmware to turn the radio into some general purpose software defined radio transmitter but that's not how the device is licensed and sold.

[jchw]

Wait, though. Doesn't that seem to make this point moot? If they're not responsible for what users do hacking around, then there's not really any need to keep firmware closed source or locked down.

To be fair, I think at least at one point, that is in fact how it worked. I recall having a wrt54g and being able to run it out-of-spec using DD-WRT.

[megous]

You can use channels not allowed in your country. The firmware doesn't prevent that.

[15155]

Where does the FCC specify the delivery format of firmware? Or what "firmware" is as a concept in general?

Non-modifiable - by whom and to what degree? One-time-programmable memory? Accepting only signed updates from the vendor? Where are these things specified in enumerated FCC regulations?

[ilyt]

Completely moot point. They are not selling a device. They are selling chip. It's on the device manufacturer to prevent it and it doesn't need to be in baseband chip.

[giantrobot]

For Part 15 devices the licensed portion of the device is the software and hardware that does the RF emission. Firmware defining operation is seen by the FCC (and other regulatory bodies in other countries) as the same thing as a circuit design of a fixed radio transmitter. To the point of firmware updates can require recertification just like a change in the BOM or circuit design would.

A RISC-V radio baseband will end up no more open than a Cortex-M one. The CPU core portion might be documented/open but not the full firmware. It'll still be effectively a black box no matter how open the specs on the processor.