Does it seem right that ACPI alone is almost 9% of the LOC in this code base? At over 165K lines?

Mind, I honestly don't know anything about the details of ACPI.

But, seems like a lot to me.

Remember that there aren't as many drivers in VMS core as in Linux (were just amd DRM driver dwarfs some older kernel versions), and ACPI for all its complexity also handles as portability layer between a lot of differences that in VMS' past involved having to release an entire special release of the system just to get it to boot, now covered by ACPI support.

Also, we don't know how much of that is test code, samples (for testing, for example)

I seems to have read somewhere that there are really only three ACPI implementations: Microsofts, Intels (used in Linux and FreeBSD, among others) and OpenBSDs. So I wonder if VMW might be a fourth, or if they are also using the Intel implementation.

ACPI is a monster. 1,100 page spec: https://uefi.org/sites/default/files/resources/ACPI_Spec_6_5...

There’s a ton of different tables you have to parse and as I recall there’s a whole bytecode you need to be able to execute.