5 ms·

Well that's horrifying. Not where I want multithreaded code. Definite risk of it being written in C with volatile~=atomic as the working assumption.

KennyBlanken 5y ago
People found the concept of computer control over an idle stabilization valve terrifying in the early 80's. Killer cars, everyone predicted. It never materialized. The lawsuits against Audi never went anywhere, and Audi even won some counter-suits. Most cars have drive-by-wire throttles. Hundreds of millions of cars out there, and DBW throttle failures leading to crashes are unheard of. You know what is an issue? Ford unable to make ignition switches that don't cause cars parked in house garages to catch fire. GM cheaping out on their own ignition switches, causing them to suddenly fail while driving....and thus shutting off the engine, ABS, and airbag systems, something that is known to have caused the deaths of half a dozen people and likely tens if not hundreds of other Cruze owners.
- cillian64 5y ago
  I don’t have a source for this but I recall reading that mechanical throttle wires are actually not especially reliable so drive-by-wire doesn’t have to be super reliable in order to be better. But perhaps it’s the same as self driving cars where people get especially disturbed by computers screwing up which sets the reliability bar higher than is otherwise logical.
  - gameswithgo 5y ago
    Have you ever had either fail on you? I never have. I have heard of a few failures but always on very modified or old vehicles. Some failure modes can happen whether actuated by wire or motor as well. it isn’t a first order concern really, dozens of higher risk, more complex things going on like tires, brakes, explosives in the steering wheels.
    - dtgriscom 5y ago
      Anecdata isn't helpful here; when you are one of millions of users, thousands of people may be inconvenienced (or killed) before you have personal experience with a problem.
- NullPrefix 5y ago
  >DBW throttle failures leading to crashes are unheard of I doubt Michael Hastings crash would have happened if he didn't drive by wire.
- sebazzz 5y ago
  > Most cars have drive-by-wire throttles. Cars where? Many cars here in Europe have a valve directly mechanically linked to the pedal. Any car without cruise control has it that way.
tonmoy 5y ago
While I agree with you in general about being careful about the pitfalls of multi-threading, the automotive industry is fairly competent at safety and correctness. They are probably the only few industry making good use of formal verification. In short, I am less worried about cars not working due to misunderstanding of C language than any other device like my PC or iPhone
tsomctl 5y ago
I've been reverse engineering a modern ABS control module. It has 2 cores, and they are separate CPU's with their own memory (although one cpu can access the RAM of the other CPU) and role. One reads/writes the CAN bus and does verification on that data, the other CPU is the one that monitors wheel speed sensors and determines when to control the solenoid valves. There is a cleanly defined area where data is copied from one CPU to the other.

KennyBlanken 5y ago

People found the concept of computer control over an idle stabilization valve terrifying in the early 80's. Killer cars, everyone predicted. It never materialized. The lawsuits against Audi never went anywhere, and Audi even won some counter-suits. Most cars have drive-by-wire throttles. Hundreds of millions of cars out there, and DBW throttle failures leading to crashes are unheard of. You know what is an issue? Ford unable to make ignition switches that don't cause cars parked in house garages to catch fire. GM cheaping out on their own ignition switches, causing them to suddenly fail while driving....and thus shutting off the engine, ABS, and airbag systems, something that is known to have caused the deaths of half a dozen people and likely tens if not hundreds of other Cruze owners.

cillian64 5y ago
I don’t have a source for this but I recall reading that mechanical throttle wires are actually not especially reliable so drive-by-wire doesn’t have to be super reliable in order to be better. But perhaps it’s the same as self driving cars where people get especially disturbed by computers screwing up which sets the reliability bar higher than is otherwise logical.
- gameswithgo 5y ago
  Have you ever had either fail on you? I never have. I have heard of a few failures but always on very modified or old vehicles. Some failure modes can happen whether actuated by wire or motor as well. it isn’t a first order concern really, dozens of higher risk, more complex things going on like tires, brakes, explosives in the steering wheels.
  - dtgriscom 5y ago
    Anecdata isn't helpful here; when you are one of millions of users, thousands of people may be inconvenienced (or killed) before you have personal experience with a problem.
NullPrefix 5y ago
>DBW throttle failures leading to crashes are unheard of I doubt Michael Hastings crash would have happened if he didn't drive by wire.
sebazzz 5y ago
> Most cars have drive-by-wire throttles. Cars where? Many cars here in Europe have a valve directly mechanically linked to the pedal. Any car without cruise control has it that way.

tonmoy 5y ago

While I agree with you in general about being careful about the pitfalls of multi-threading, the automotive industry is fairly competent at safety and correctness. They are probably the only few industry making good use of formal verification. In short, I am less worried about cars not working due to misunderstanding of C language than any other device like my PC or iPhone

tsomctl 5y ago

I've been reverse engineering a modern ABS control module. It has 2 cores, and they are separate CPU's with their own memory (although one cpu can access the RAM of the other CPU) and role. One reads/writes the CAN bus and does verification on that data, the other CPU is the one that monitors wheel speed sensors and determines when to control the solenoid valves. There is a cleanly defined area where data is copied from one CPU to the other.