1. Introduction: What is an ACPI _HID ? The Advanced Configuration and Power Interface (ACPI) provides a bridge between firmware, hardware, and the operating system. One of its core constructs is the Hardware ID ( _HID ) – a string that uniquely identifies a device in the DSDT (Differentiated System Description Table) or SSDT (Secondary System Description Table).
The specific string:
In Linux, x86_model = 58 matches INTEL_FAM6_IVYBRIDGE . This identifier is not stored in the ACPI tables as a literal. Instead, it is constructed dynamically by the Linux kernel’s ACPI CPU driver. Code Path (Linux kernel example) In drivers/acpi/processor_core.c , the function acpi_processor_get_info() does something like:
For system administrators or embedded developers working with Ivy Bridge platforms, understanding this ID helps debug ACPI power state issues, especially when _CST (C-states) or _PSS (P-states) are incorrectly reported by buggy firmware.
