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0 pointss_q_b12y ago0 comments

> for example a near-real-time flight application.

Primarily latency. Now, ideally you'd like the entire subsystem moved off disk into volatile memory, but for some things you're going to have to read from disk. I can imagine cases where that wouldn't be easily feasible if the drive had NSA crypto.

"Regarding the Russians: Oh, I see, now. Yes, you're right that if country X cracks our encryption, we can't assume that they didn't get help from <insert China or Russia here>."

Right, but its more than that in the case of the Iranians. The Russians have a long and documented history of assistance to the Iranians and the Syrians.

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javert12y ago· 2 in thread

> for some things you're going to have to read from disk.

I'm not sure I follow. For some things you're going to have to _write_ to disk... like captured video. (I wouldn't consider that to be the "real-time" part of the software, though.) And you might have to read from disk occasionally... maybe you have map information stored there... but that probably doesn't need to be real-time. Can you tell me an example where you would need to read from disk in real-time? (Which I think should anyway be impossible, regardless of whether or not heavy crypto is being used.)

> The Russians have a long and documented history of assistance to the Iranians and the Syrians.

Yeah, very true, I have noticed that, too.

s_q_bOP12y ago

Sure! Man I love when people on hn ask genuine questions rather than trying to one up one another. It's one of the reasons I was so reluctant to stop lurking for so long.

Much like the Mars rovers, the navigation system is loaded in a modular fashion, with complex algorithms for each scenario loaded on the fly. So for example, imagine a UAV goes into a stall. Likely the aircraft needs a whole new set of algorithms to recover. It's very likely I this case you'd need low latency disk reads. Now again, this is just a guess based upon my experience with similar systems. I've never developed a UAV system.

javert12y ago

> Man I love when people on hn ask genuine questions rather than trying to one up one another. It's one of the reasons I was so reluctant to stop lurking for so long.

Well then, you're exactly the kind of person we need to stop lurking and start participating, so welcome aboard. But yeah, I totally understand you.

> this is just a guess based upon my experience with similar systems

You mean planetary rovers? If not, can you be more specific? I realize it's not necessarily wise to divulge too much industrial information. I actually have worked on UAVs... not to the point that I can say the scenario you're presenting is incorrect (I wasn't involved in that kind of stuff), but I don't think it's very plausible. I could see that strategy being more reasonable on a super memory-constrained device where the system is radiation hardened, like space equipment. I would think for a normal UAV, you'd just keep all the code (algorithms) you might need in memory.

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