APM - Advanced Power Management

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In order to use APM with Linux on the Vaio-505 it is necessary to configure the Linux kernel so that it supports APM. When configuring the kernel (either using one of make config, make menuconfig or make xconfig) the APM settings are found under the "Character Devices" section. Here are the settings I used:

   Advanced Power Management BIOS support (CONFIG_APM) [Y/n/?] Y
   Ignore USER SUSPEND (CONFIG_APM_IGNORE_USER_SUSPEND) [N/y/?] N
   Enable PM at boot time (CONFIG_APM_DO_ENABLE) [Y/n/?] Y
   Make CPU Idle calls when idle (CONFIG_APM_CPU_IDLE) [Y/n/?] Y
   Enable console blanking using APM (CONFIG_APM_DISPLAY_BLANK) [N/y/?] N

   Power off on shutdown (CONFIG_APM_POWER_OFF) [Y/n/?] Y
   Ignore multiple suspend (CONFIG_APM_IGNORE_MULTIPLE_SUSPEND) [N/y/?] N

This is for a 2.0.x kernel. The 2.2.x development kernels will offer some more choices.

It took me a while to figure out why I always got the wrong time whenever I suspended the notebook (once I noticed that the time was wrong). If your hardware clock is set to GMT time, you have to give the "-u" or "--utc" switch when starting the apmd daemon, so that it can use this information when setting the time after a resume operation. Sometime it really makes sense to read the documentation before installing new software :-)