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I would like to know a related thing with regards to mac EFI firmware. Does it support low battery ACPI events? How does macOS trigger low battery alarms? By polling?

I'm running Linux on my MacBook and it is irritating I cannot use a simple udev rule on to trigger suspend. To be fair most PCs don't support this either. Only some ThinkPads. It's usually my litmus test for Linux compatibility.

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Macs use the ACPI Smart Battery Subsystem. The Linux SBS driver should be polling regularly and also receive GPEs when the battery reaches certain thesholds. But the polling frequency should be in the order of seconds, providing constant battery level progress and time to suspend at a critical condition.

Thanks. I didn't know SBS was the particular kernel module responsible for this. However, lsmod reports it's loaded by default in my stock Arch kernel and I assume it has always been.

I have never been able to get events through acpi_listen when the battery reaches particular thresholds. Thus, udev rules for critical battery levels never work.

Any ideas why this is not working? I'm using a MBA 11 inch late 2012. Possibly the most Linux-compatible Mac machine ever. All stock Intel hardware.

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