3 ms·
none of these was done "on purpose" which is the definition of a shenanigan. The “shenanigans” are that it has become acceptable practice to cut corners on sec
by gaius 9y ago
none of these was done "on purpose" which is the definition of a shenanigan.
The “shenanigans” are that it has become acceptable practice to cut corners on security to improve benchmarks.
Maybe speculative execution is just a thing that shouldn’t be done? People computed perfectly well before it. Itanium isn’t impacted by Meltdown so Intel is capable of it.
- sniglom 9y agoIntel is discontinuing Itanium. One of the reasons it didn't go well was probably due to the way it was designed.
- netheril96 9y agoSo, how do you propose we punish them with the market power? Abandon all products with CPUs in?
- coldtea 9y ago>The “shenanigans” are that it has become acceptable practice to cut corners on security to improve benchmarks. Nobody "cut corners". Those were unexpected bugs that took more than a decade for someone to even discover, not some deliberate decision to sacrifice security for performance. >Maybe speculative execution is just a thing that shouldn’t be done? No, it should 100% be done. >People computed perfectly well before it. Perfectly slowly too. >Itanium isn’t impacted by Meltdown so Intel is capable of it. Itanium tanked.
- gaius 9y agoNobody "cut corners". What do you call accessing memory before checking permissions then? AMD do the check! Perfectly slowly too. A simple predictor that assumes backwards branches will be taken (loops) and forward branches (most likely exceptions) will not is really all you need, if you insist.
- lorenzhs 9y agoYou appear to be confusing Meltdown and Spectre. This is about Spectre Variant 2. You're describing Meltdown. Also, the fault is queued and not discarded. If the branch ends up being taken, you'll get a fault for accessing a forbidden part of memory. If not, the CPU "undoes" the speculatively executed part as if it never happened. The Meltdown issue is that it doesn't undo the cache effects, which nobody thought to be a big deal, and which are very hard to undo. Also, you severely underestimate the speedups gained by a better branch predictor. There's a nice writeup at https://danluu.com/branch-prediction/ https://danluu.com/branch-prediction/ if you're interested.