Advanced Configuration and Power Interface (ACPI)
ACPI is how every OS discovers hardware topology, manages CPU power states, handles thermal throttling, and receives platform events. Required for kernel, power management, and firmware development on all modern x86/Arm platforms.
What It Defines
Defines the OS-directed power management and hardware configuration interface between firmware and OS. Covers the ACPI table hierarchy (RSDP → RSDT/XSDT → DSDT/SSDT), power state transitions (global S0–S5 sleep states, CPU C-states, P-states for DVFS), ACPI Machine Language (AML) bytecode for describing device topology, thermal management zones, PCIe hot-plug events, and GPIO controllers. The OS ACPICA interpreter executes AML at runtime.
Canonical (Normative)
Related References
Industry consortium (Intel, AMD, ARM, Apple, Microsoft, HP, Dell, AMI, Phoenix) that owns and maintains the UEFI Specification and ACPI Specification. UEFI replaces legacy BIOS as the firmware interface for all modern x86-64, AArch64, and RISC-V platforms. ACPI defines OS-directed power management and hardware configuration via descriptor tables and AML bytecode.
Related Specs
Every modern x86-64 and AArch64 server, workstation, and PC uses UEFI. Required for OS development, bootloader work (GRUB, systemd-boot, shim), Secure Boot policy, and firmware engineering.
SMBIOS is how software reads hardware inventory: CPU model, RAM config, system UUID, and BIOS version. Cloud hypervisors inject SMBIOS tables to identify instance type; asset management tools harvest them for CMDB population.