acpidump: Add -T TBLN to print a specific ACPI fixed table

[imp]

Summary

Add the ability to dump a specific ACPI table rather than all of them.

Sponsored by: Netflix

[bz]

usr.sbin/acpi/acpidump/acpi.c

2552

I wonder if I would put that check into the caller. Here at first I thought it's an error but in fact it's just "not that one, skip".
While having an explicit continue in the caller makes that more obvious.
(personal feeling; feel free to ignore)

[imp]

usr.sbin/acpi/acpidump/acpi.c

2552

I think it's fine like this.
There's bigger structural problems with this code, like the series of ugly if statements that should just be a loop. And the fact this should be more like a callback than this this current structure. I plan on adding this functionality to the boot loader to help diagnose more issues there, and will revisit the structural issues at that time so I come up with a better structure that can be shared between both of them.

[andrew]

usr.sbin/acpi/acpidump/acpi.c

2552

Can we use sizeof(sdp->Signature) or ACPI_NAMESEG_SIZE rather than 4?

2603

And here

[imp]

usr.sbin/acpi/acpidump/acpi.c

2552

I'll do a quick followup commit for this.

[imp]

update with andy's suggestions (I reworked things differently than I thought
I would in earlier comments).