Thank you! So I should choose ACPI when I build a kernel since my board supports it and disable APM.
> On Fri, 2002-12-20 at 23:14, Brett I. Holcomb wrote: >> What is the difference in APM vs ACPI for power management? Are they two >> exclusive methods of controling shutdown, etc. or is ACPI an advanced >> version of APM? When I build a kernel can I specify both or do I choose >> one? > > > Well, here is the difference between the two (At least as I understand > it): > > APM is a a BIOS-based scheme of system power management. It provides CPU > and device power management and uses device activity timeouts to > determine when to transition devices to low power states. > > However, APM falls short: > > 1.) Every BIOS has its own power management scheme. There is no > consistancy between manufacturers. Each BIOS developer must refine and > maintain their own APM BIOS code and functionality. > > > 2.) The reason for a suspend is never known. > > > 3.) The BIOS is unaware what the user is doing. Ultimately, the BIOS > makes a mess of everything. > > 4.) The BIOS knows nothing about USB devices, add-in cards and IEEE 1394 > devices. > > > ACPI was developed to overcome the deficiencies in APM. ACPI (Advanced > Configuration and Power Interface) is an open industry specification. > > ACPI evolves the existing collection of power management BIOS code, > Advanced Power Management (APM) application programming interfaces > (APIs, PNPBIOS APIs, Multiprocessor Specification (MPS) tables and so on > into a well-defined power management and configuration interface > specification. The specification enables new power management technology > to evolve independently in operating systems and hardware while ensuring > that they continue to work together. > > Unlike APM, ACPI allows the Operating System (instead of the BIOS) to > control Power Management (OSPM). The support code provided by the BIOS > is not written in the native assembly language of the platform but in > AML (ACPI Machine Language). The BIOS does not determine the policies or > time-outs for power management or resource management. > > > There are 4 device states under APM: Enabled, Standby, Suspend and Off. > > ACPI's device states are extended, with 4 major global states: Working > (S0), Sleeping (S1-S3), Soft-Off (S4), and Mechanical-Off (S5). Sleeping > is further broken down into 3 substates.The ACPI BIOS tables define what > these states mean for individual devices, and the operating system > determines when to move a device, or even the entire system, from one > state to another. > > The ACPI-compatible OS mainly acts as a swap manager that swap the > computer to different state based on the information collected. A > transition from one state to another is first started with the OSPM > system code which instructs the OS kernel for the specific state > transition. After the kernel receives the instruction, it asks the > appropriate device driver to perform the operation. Response from the > operation will be passed back to the OSPM from the kernel. This process > will proceed in hierarchical order until all devices and components > reach a specified state. > > There is more, but the above info is probably enough............... > > > > Best > > Peck -- Brett I. Holcomb [EMAIL PROTECTED] AKA Grunt <>< Registered Linux User #188143 Remove R777 to email _______________________________________________ Linux-users mailing list [EMAIL PROTECTED] Unsubscribe/Suspend/Etc -> http://www.linux-sxs.org/mailman/listinfo/linux-users
