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FTA: In standby, the monitor is actually disconnected and disappears from the I/O Registry I think the common case of “multiple HDMI ports” is one where users
by Someone 4y ago
FTA: In standby, the monitor is actually disconnected and disappears from the I/O Registry
I think the common case of “multiple HDMI ports” is one where users plug in USB-C dongles to magically create them.
In that case, do the HDMI ports disappear from the registry, too, so that you can’t identify ports across standby?
Even distinguishing a built-in HDMI port from one in a USB-C dongle may be difficult if the built-in one secretly is connected over USB-C.
- akira2501 4y agoThe USB is a bus. All controllers and devices connected to it have a unique port assignment as well.
- Someone 4y agoMy question is whether that assignment survives standby of the PC. Reading https://unix.stackexchange.com/questions/336037/mapping-of-usb-device-changes-afer-rtcwakeup https://unix.stackexchange.com/questions/336037/mapping-of-u..., I’m not sure it does. Certainly, a bus scan has to happen to detect whether devices (including USB hubs) got unplugged or plugged in during standby, so if that scanning isn’t guaranteed to always produce the same result (e.g. because of jitter in the timing when various devices come online), I doubt that’s guaranteed to produce 100% identical information. It’s a question, though. I don’t know enough of how this work to definitely answer that.
- IshKebab 4y agoThat answer is talking about the kernel assigned device names, not the port identifiers which should be stable across reboots.