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Comment by devy | Hacker News Reader

If the infotainment system caused the MCUs to reboot while someone traveling "130mph on San Mateo Bridge" and that caused the break system to segfault due to unconventional way of loading parts firmware, it might be a life&death situation, easily. Examples in that threads go on, literally hundreds!

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Well, you can reboot the system while driving(both console and dash), nothing special happens other than the AC turning off for a brief period of time. Brakes, wheel, throttle all respond normally.

Source: Done this a few times to clear bad map data or occasional glitch.

Doesn't surprise me -- a couple of times my new 3 has had nothing on the display but it's still happy to let me put it in gear and drive away, and the display pops up within a second or two.

To be sure, it's a bit unsettling, and I wouldn't be thrilled about it deciding to not work for a day or two, but, in a way, it makes me MORE comfortable that the vehicle control systems function as expected.

AC should be considered mission critical.

Definitely, I'd put it on the mission criticality list right below inflight wifi.

It's not mission critical, but it's important: in cold weather the windshield can fog up to the point of 0% visibility.

In hot weather it can become very uncomfortable or even impossible to drive without AC.

There’s a distinction between safety critical equipment and essential equipment. If the former fails, it could kill you. If the latter fails, you can’t drive anymore but you won’t die if it happens on the road. Brakes are in the former category, while things like HVAC and instruments are in the latter.

Safety equipment must not fail, but essential equipment can fail as much as your customers will tolerate.

You can steal a trick the motorcycle community discovered a long time ago, some water + soap on the windshield prevents condensation.

Our '83 Vanagon doesn't have AC, it can be uncomfortable but sure isn't the end of the world.

Seriously yes, at least ventilation. Anybody who don't believe this, try turn off your AC completely and see how quickly your wind screen is fogged up to the point you can't see out. (depending on which climate you live in)

I don't understand how that could happen. MCU reboots, ???, brake system segfaults? What goes in the middle?

Probably everything has access to everything on the CAN bus.

IIRC car manufactures are irresponsibly lazy and never properly air-gap infotainment from critical stuff.

There's a firewall between the CAN bus so it cannot be affected at all by the MCU.

Even if this were true (and as another commenter says, it's not) I don't see how that fills in this gap. It would make sense if the first step were "MCU goes crazy," but not with a simple reboot.

There’s no concept of “reboot” with MCUs, since there’s usually no OS. Likewise there’s usually no concept of segfault, because segfault requires memory protection which is something most MCUs don’t use.

Tesla’s MCU runs Linux. Older ones use a 2012-era Nvidia mobile SoC, while newer ones use something from Intel.

Nah. No way the mcu responsible for braking would run an OS

Didn't they already do an Over-the-Air update to fix the braking time in response to a bad review?

You don’t need an OS for that.

This must be an acronym mixup. We’re talking about the Media Control Unit, i.e. the giant screen in the center of the dashboard responsible for zero safety-critical systems.

MCU in the case of braking and steering is “micro controller unit”.

Yeah, those definitely aren’t running Linux, and the guy here wasn’t working on them.

Yes, The infotainment stuff, like the screen, internal lights, speakers are connected via a low profile third bus system, certainly not the main CAN bus or profibus or firewire. Some, like in the BMW even via WiFi. These are the systems usually used with Linux or Windows or Android. On top of the important stuff.

s/reboot/reset/, s/segfault/bus-fault/

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