Datasheet

“main” (Installation and Administration) — 2004/6/25 — 13:29 — page 362 — #388

APMD_TURN_OFF_IDEDMA_BEFORE_SUSPEND

Sometimes, resuming after a suspend may not work if an IDE device

(hard disk) is still in DMA mode.

Other options include the possibility to correct the key repeat rate or the

clock after a suspend or to shut down the laptop automatically when the

APM BIOS send a “battery critical” event. To execute special actions, adapt

the script /usr/sbin/apmd_proxy (performs the tasks listed above) to

your needs.

17.2.2 Further Commands

apmd contains a number of useful tools. apm can be used to query the cur-

rent battery charge level and to set the system to standby (apm -S) or sus-

pend (apm -s). Refer to the manual page of apm. The command apmsleep

suspends the system for a speciﬁed time. To watch a log ﬁle without keep-

ing the hard disk spinning, use tailf instead of tail -f.

There are also tools for the X Window System. apmd contains the graphi-

cal utility xapm for displaying the battery charge level. If you use the KDE

desktop or at least kpanel, use kbatmon to view the battery charge level

and suspend the system. xosview is another interesting alternative.

17.3 ACPI

ACPI (advanced conﬁguration and power interface) was designed to en-

able the operating system to set up and control the individual hardware

components. ACPI supersedes both PnP and APM. It delivers information

about the battery, AC adapter, temperature, fan, and system events, like

“close lid” or “battery low.”

The BIOS provides tables containing information about the individual com-

ponents and hardware access methods. The operating system uses this in-

formation for tasks like assigning interrupts or activating and deactivat-

ing components. As the operating system executes commands stored in

the BIOS, the functionality depends on the BIOS implementation. The ta-

bles ACPI is able to detect and load are reported in /var/log/boot.msg.

See Section 17.3.4 on page 366 for more information about troubleshooting

ACPI problems.

362 17.3. ACPI