arm64/acpi: Give the real PA limit to ACPI

[scottph]

Summary

Read PA bits from ID_AA64MMFR0_EL1.PARange.

MFC after: 1 week
Sponsored by: Ampere Computing, Inc.

[andrew]

You should use get_kernel_reg to read the ID registers when we need a common version over all CPUs. It's not going to affect it here, but when use later in the boot it can as on a big.LITTLE system these ID registers can sometimes be different across the different core types.

sys/arm64/acpica/acpi_machdep.c

252

This should be ID_AA64MMFR0_PARange_VAL(mmfr0) Maybe with >> ID_AA64MMFR0_PARange_SHIFT, although the shift is 0 so it might be easier to add a comment to make this knowledge explicit.

[markj]

sys/arm64/acpica/acpi_machdep.c

281

You might print the value itself in this message.