SDB:General Information concerning ACPI Support

Version: 8.1 -

The management of interrupts has always been a tricky issue of PC hardware. Simply stated, interrupts are the signals that tell the processor when to interrupt a running job in order for another request to be processed by the processor. This is also linked to the power management, which determines the time span during which no request was sent to the processor. Accordingly, it can switch to various power saving modes.

The previous power management standards were APM and PNPBIOS. The new standard is called ACPI (Advanced Configuration and Power Interface specification), and is praised as the successor of APM and PNPBIOS. Additional features of ACPI include the description of the hardware (CPU, bus, ...) as well as some additional minor jobs beyond the power management. Furthermore, the APIC (Advanced Programmable Interrupt Controller) is another technology for the interrupt management. Unfortunately, the similarity of the abbreviations is rather confusing.

As more and more new computer systems without APM and PNPBIOS support enter the market, the operating systems too must support ACPI. As the successor of APM and PNPBIOS, ACPI was supposed to eliminate the problems that were frequently encountered due to incorrect APM implementations of the BIOS manufacturers. However, due to its much larger complexity, ACPI too has led to many defective implementations. Especially computers that support both ACPI as well as the old APM/PNPBIOS are affected by these symptoms. Using so-called "blacklists", the operating system determines whether APM/PNPBIOS or ACPI is more suitable for a specific computer model, in case the BIOS indicates that both are supported.

However, due to this technology switch, the said problems may lead to unexpected errors on some systems. Computers whose ACPI support is defective but which are not included in the blacklist of the Linux kernel may freeze when the kernel is booted or not be able to correctly detect some of PCI cards. This problem can be tackled by means of boot options that partially or entirely deactivate ACPI.

In case any of the above-mentioned problems should occur during or after the installation of SUSE LINUX 8.1, you need to enter a kernel parameter during the installation. The procedure is described in our Support Database under the following URL:

SDB:Kernel Parameters for ACPI/APIC <keyword>acpi,kernel,parameter,irq,power,management,apm,apic,interrupt,controller,boot,option</keyword>