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Date: Mon, 5 Feb 2024 13:03:33 -0600
From: Doug McIntyre <merlyn@geeks.org>
To: FreeBSD Questions <freebsd-questions@freebsd.org>
Subject: Re: acpi0 device
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On Mon, Feb 05, 2024 at 01:27:30PM +0100, Rocky Hotas wrote:
> But what does it exactly represent? Is it just a logical starting point
> for the device tree, or is there some physical device behind it?

Its the abstracted version of the X86/X64 hardware/BIOS on all modern hardware for the OS layer. 

Starting with the Wikipedia page would be a good intro.
https://en.wikipedia.org/wiki/ACPI