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Lightning video adapters feature Apple Secure Boot, run Darwin kernel
- bri3d 7y agoPrevious discussion of XNU/Secure Boot on Lightning video adapters (2013) : https://news.ycombinator.com/item?id=5307781 https://news.ycombinator.com/item?id=5307781 . This thread has some new information and maybe people will start playing with these more eventually.
- throwaway3627 7y agoMakes you wonder if some rogue device/adapter/charger could deliver malware (sploit/trickery) to it before or after it's booted from the host.
- reaperducer 7y agoUnlikely since the Apple adapter contains no software. The firmware is loaded by the host device when it's plugged in.
- CGamesPlay 7y agoDoesn’t that mean that a rogue device that did contain software and ignored the incoming packet might actually be trusted by the host device when it shouldn’t be? The twitter thread did say the firmware payload contained no personalization (like encryption keys, perhaps).
- saagarjha 7y ago> The twitter thread did say the firmware payload contained no personalization (like encryption keys, perhaps). To be clear, this just means that the firmware isn't tied to a specific device via the normal ECID/nonce pair like a normal iOS update is.
- citrusui 7y agoFor more context, check out this comment on the Panic Blog: https://panic.com/blog/the-lightning-digital-av-adapter-surprise/#comment-16841 https://panic.com/blog/the-lightning-digital-av-adapter-surp...
- stefan_ 7y agoDon't drink the kool-aid. An adapter that destructively compresses the signal is an unexpected and unmitigated disaster, not some cool quirk of Lightning that makes "the host not care what is hanging off it". The real reason this abomination exists is because as recently as 2018, Apple is selling products with a connector that has the equivalent bandwidth of USB 2, not even close to transporting a single 1080p video signal.
- lloeki 7y agoIt’s destructive, and it probably also introduces a quite decent amount of latency.
- bscphil 7y agoYes - this is really quite astonishing. I imagine any video professional would be horrified to learn that their CABLES were recompressing their video. There's never an acceptable reason for that it's really amazing I haven't heard about it before.
- tinus_hn 7y agoI wonder what they use for the demos at WWDC.
- throwaway3627 7y agoThat's some cool enginerding discovered by gindrenigne. AvE, bigclivedotcom and EEVblog would be proud!
- deleted 7y ago[deleted]
- dingo_bat 7y agoKind of insane that we need a secondary computer to let a $2500 laptop output video to a screen.
- faissaloo 7y agoWhy on earth would you need a kernel in your adapter
- quonn 7y agoIf only a comparatively small number of adapters is produced and you already have the SoC and the kernel, it may be cheaper to develop than anything else.
- bri3d 7y agoThere are kernels running in almost every piece of peripheral hardware you own. If you have a modern WiFi chipset, LTE baseband, or GPU it's certainly running an RTOS kernel. Once you switch to a packet-based protocol with multiple concurrent tasks (decode, packet receive, link negotiation, etc.), it just makes sense - either you're implementing timeslicing / scheduling on your own or you can let someone else do it. The issue that causes poor video quality isn't that Apple chose to run XNU or use an SoC for their adapter, it's that they chose to use H.264 at a low bitrate due to hardware support constraints rather than another encoding scheme which could offer less lossy video.