ACPI in Linux - Myths Vs. Reality

Overview

Major Linux distributors have been shipping ACPI in Linux for several years, yet mis-perceptions about ACPI persist in the Linux community. This paper addresses the most common myths about ACPI in Linux. When users boot in ACPI-mode instead of legacy-mode, the first thing they notice is that the power button is now under software control. In legacy-mode, it is a physical switch which immediately removes power. In ACPI mode, the button interrupts the OS, which can shutdown gracefully. Indeed, ACPI standardizes the power, sleep, and lid buttons and the OS can map them to whatever actions it likes. In addition to standardizing power button events, ACPI also standardizes how the OS invokes software controlled power-off.