Add a kernel env to select between acpi and fdt

[andrew]

Summary

This allows the user to select their preferred order between ACPI and
FDT. This will be needed on machines with both, e.g. the SoftIron
Overdrive 3000. The kernel will accept one or more comma separated
values of either 'acpi' or 'fdt'. Any other values are skipped.

To set it the user can either set it on the loader command line, or
in loader.confm e.g. in loader.conf:
boot_order=acpi,fdt

I'm not complety happy with the name, and am happy to change it if
someone comes up with something better.

[emaste]

I'm not complety happy with the name, and am happy to change it if
someone comes up with something better.

I agree, boot_order seems to imply something to do with boot device ordering. Maybe cfginfo_order, config_info_order, etc.?

[emaste]

sys/arm64/arm64/machdep.c

827–828 ↗

(On Diff #18637)

Reverse order of strncmp and bus_order[] test (what happens if you have a string < 4 chars).

[andrew]

Rename to cfginfo_order and fix a possible buffer overflow

[emaste]

seems ok to me

[imp]

sys/arm64/arm64/machdep.c

822 ↗

(On Diff #18660)

I'd be tempted to make this be a kern.cfg.order=fdt,acpi and then report kern.cfg.type=fdt or acpi depending on what was selected.

848 ↗

(On Diff #18660)

else panic or error message? Though I guess since this is called before cninit, that won't do much good....

sys/arm64/arm64/nexus.c

415 ↗

(On Diff #18660)

The first part of this if is sufficient. It can't be == AMD64_BUS_FDT when OF_PEER(0) == 0.

[andrew]

sys/arm64/arm64/machdep.c

848 ↗

(On Diff #18660)

The panic should be after cninit and should only happen if the user selected an order that we couldn't handle, i.e. env != NULL && arm64_bus_method == ARM64_BUS_NONE.

[andrew]

Update based on feedback

[andrew]

sys/arm64/arm64/nexus.c

459 ↗

(On Diff #18742)

This one will be needed, it probes the tables. Otherwise I think this is ready.

[andrew]

Call acpi_identify, it's needed to walk the ACPI tables by the children