Of course, most ordinary users, as evidenced by reviews and posts on various forums on the Internet, usually don’t get into the intricacies of setting up their own computer system, relying almost entirely on the automated means of the operating system and know nothing about ACPI technology. What is it, then we will try to figure it out, touching on the technical side of the issue, setting out all the theses in the most understandable language, and its practical application. But it’s worth mentioning right away that in a slightly different version almost everyone knows about it.
ACPI: what is it generally understood?
It’s worth starting with the definition of the term itself. The abbreviation ACPI is derived from the English phrase Advanced Configuration and Power Interface, which can be interpreted as "advanced (advanced) configuration and power management interface." This standard has become an integral attribute of modern computers, including not only server systems, but also desktop PCs. The general and main task of using this technology is to maximize the flexibility of managing the power of the computer and all the equipment installed in it by ensuring clear interaction between the hardware, the primary input / output system of the BIOS of the motherboard, the operating system and the applications installed in its environment.
What is this technology for?
This is a common understanding of ACPI technology. From a practical point of view, everyone knows what it is, although they don’t realize that this technology is used in some cases. Thanks to its implementation, it became possible to control the power of the computer in such a way that, say, like any other household or mobile equipment, it was always ready to perform some important programmed actions. A comparison can result in the following. Suppose you go to bed, but at night you need to record some TV show or movie from the TV. You leave the recorder in sleep mode (Standby), but set the start and end time of recording in advance, and recording is done without your participation, since the device turns on at a certain moment, and then, when the recording is finished, it turns off again. So with computers. Feedback from users and experts suggests that the installation of the time for installing updates at night is nothing more than the use of ACPI technology. What this is can be understood by another example.
Relatively recently, in stationary computers and laptops, it became possible not to turn them off when you are not working with them, but to leave them either in sleep mode or in hibernation state. In the same way, you can program the computer to turn on or off at a specific time. Again, this power management is provided through the use of ACPI technology.
If you look even at all the latest modifications of Windows, it is easy to notice that when they are used on the same laptops, you can even configure the actions that will be performed when the power button is pressed or when the lid is closed. True, it is believed that this technology was initially more widespread after all in the "apple" computer and mobile systems, despite the fact that Microsoft was at the source of the introduction of this technology.
A bit of history
Indeed, the first mention of this standard dates back to 1999, when Microsoft, Toshiba, Intel, HP and Phoenix tried to jointly implement power management technology. After a fairly long period of time, in 2006 the specification of version 2.0 was introduced. Modification 6.2, released in 2017, is widely used today.
Brief technical information
So, with the provision of interaction between different components of a computer system, we figured it out. But what do you think should be given priority? Both BIOS, OS, and installed programs (usually hardware drivers) are struggling for power management. Based on the fact that it was Microsoft that was the founder of this standard, it is easy to figure out that the specialists who developed this technology tried to make it so that the priority of computer power management was transferred to Windows, rather than being concentrated in the hands of the primary BIOS system. The prototype of the current standard was the previously used APM standard, which had a number of drawbacks because it did not resolve some conflicts between the BIOS and Windows. But the use of ACPI in Windows made it possible to provide the operating system with wider rights, which before, so to speak, were heavily infringed. All of this combined allowed the use of several different power supply circuits in the Windows systems themselves.
For example, now you can set high performance, a balanced circuit, reduced power consumption or create your own circuit by changing many additional parameters directly in Windows. Thus, the installation of the corresponding options in the BIOS has become almost unclaimed (although sometimes such settings are also necessary).
System states
Now a few words about how this all works. It is generally accepted that a computer system can be in four basic states:
- G0 - normal functioning;
- G1 - state of sleep;
- G2 - soft shutdown of the system without complete blackout with readiness to turn on at any time (automatically or on demand);
- G3 - full shutdown (in relation to stationary PCs with blackout and ATX cases).
The creators of the technology tried to expand the second state (G1) by introducing additional options:
- S1 - disabling all processors and devices not specified in the specification with resetting the cache and stopping tasks, but with power to all CPUs and RAM.
- S2 - a deeper sleep state with the CPU off (usually not used).
- S3 - sleep state, when only random access memory remains active, and the user can resume work without losing data in the state in which they were while falling asleep.
- S4 - an analogue of S3 in the form of hibernation, when the RAM is turned off, and the data is stored in non-volatile memory.
ACPI Management in BIOS
When configuring ACPI parameters, it should be noted that such a technology can only be used if it is supported by the BIOS, the operating system, and installed equipment. By and large, developers of all modern primary systems, including those equipped with the new UEFI interface, always include ACPI parameters in the list of custom options.
This section is usually called Power Management Setup, ACPI Congiguration, ACPI Suspend Type, or has a similar name. In principle, an ignorant user does not need to change the options, so experts do not recommend entering such settings without special need, which is confirmed by numerous reviews and tips on online forums. But for those who want to use some additional features of their PC, you can usually offer to activate remote “waking up” the PC via the network or when the modem rings, when you move the mouse or when connecting a USB device, etc. By the way, by the power of ports and devices USB or the same network adapters can be controlled directly in Windows, using the setting of prohibitions or permissions to turn off / on.
Driver installation
As for the management software, usually the Windows 10 ACPI driver or its relatives a little lower rank are installed independently at the installation stage of the OS itself. If this does not happen, you should check the technical specifications of your PC, laptop or installed equipment (primarily the motherboard) for ACPI support.
What to do if the driver does not install or installs incorrectly?
But sometimes you can meet situations where it seems that both the system, equipment, and BIOS support this technology, but the ACPI driver is still not installed or is not installed correctly. There is nothing surprising in this, since the operating system itself searches for drivers exclusively in its own databases or in Microsoft storages, and only for those devices for which corporation support is claimed. But what if you have some non-standard equipment installed? The way out of this situation will be an independent search and installation of the necessary control software, based on only two identifiers.
Just call the “Device Manager”, through the properties of the selected component, go to its properties, go to the details tab, select the display of the equipment ID from the drop-down list, and then look at the longest line, which will contain something like ACPI_VEN_INT_DEV with the additional numbers indicated . It is the identifiers DEV and VEN that allow the most accurate initialization of an unknown device. On the longest line, you just need to search for a driver on the Internet, download it to your computer, and then install it manually.