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I'm unsure of the security of simultaneous multithreading on modern Apple CPUs
by ldng 5y ago
I'm unsure of the security of simultaneous multithreading on modern Apple CPUs
- MiguelHudnandez 5y agoCan you share some of your research about it?
- eyelidlessness 5y agoI’m unsure of the existence of simultaneous multithreading on Apple CPUs.
- garren 5y agoApple cpus specifically, or arm64 in general? The same class of bug (i.e., speculative execution) or something else altogether? I’ve found myself with more and more arm hardware these days, and I’d assumed (probably incorrectly) that it wasn’t as prone to these kinds of issues.
- sam0x17 5y agoI'm unsure of the security of anything on modern Apple operating systems or hardware, since I can't review the source code or hardware schematics.
- emteycz 5y agoCan you send me the Intel/AMD/Qualcomm/Samsung sources and schematics?
- mhh__ 5y agoIntel at very least do publish a pretty hefty optimization manual. We do have a bunch of leaked intel firmware, or so I'm told...
- macdice 5y agoI haven't followed it or tried it, but supposedly you can boot up a pure open source Darwin system. Certainly it has been very useful for me as a cross-platform developer to be able to browse its source and understand quirks of system calls etc. Are you saying that key parts you'd like to review are closed source? Hmm, the new file system is closed source, which is a clue, but I don't know to what extent Darwin is "different" from what macOS is really running...
- brirec 5y agoI haven’t kept up with this too much lately, but to my knowledge there is very little documentation or working code to set up a Darwin environment from scratch with FOSS, and there aren’t any modern Darwin “distributions” because of this difficulty and lack of documentation and code. I wish this weren’t the case, but whatever PureDarwin has right now is probably about the closest you can get to a Darwin environment that boots without nonfree code.
- dmitrygr 5y ago> simultaneous multithreading on modern Apple CPUs reply Where did you find such a thing?
- reasonabl_human 5y agoI’m not well versed in architecture intricacies of arm64, simultaneous multithreading doesn’t exist on those platforms?
- dragontamer 5y agoArchitecture: ARMv8 or ARMv7. Microarchitecture: Neoverse N2, NeoverseE1, Apple Firestorm (all the same ARMv8 architecture, but all different microarchitectures) Of these: Neoverse E1 has SMT. Apple Firestorm does not.
- floatboth 5y agoCavium ThunderX2 (RIP) had 4-way SMT