power: employ services feature

features.in/power/config.mk

 +power: use/power/acpi/button use/power/acpi/cpufreq; @:
 
 # common
-# TODO: invent multi-target scripts and integrate that 08-powerbutton
-use/power:
+use/power: sub/rootfs use/services
 	@$(call add_feature)
 	@$(call add,COMMON_PACKAGES,installer-feature-powerbutton-stage3)
 
 # modern power management
 use/power/acpi: use/power
 	@$(call add,COMMON_PACKAGES,acpid acpi)
+	@$(call add,DEFAULT_SERVICES_ENABLE,acpid)
 
 use/power/acpi/button: use/power/acpi
 	@$(call add,COMMON_PACKAGES,acpid-events-power)
@@ -18,7 +18,10 @@ use/power/acpi/cpufreq: use/power/acpi
 
 use/power/acpi/powersave: use/power/acpi
 	@$(call add,COMMON_PACKAGES,powersave)
+	@$(call add,DEFAULT_SERVICES_DISABLE,acpid)	# override
+	@$(call add,DEFAULT_SERVICES_ENABLE,powersaved)
 
 # legacy power management
 use/power/apm: use/power
 	@$(call add,COMMON_PACKAGES,apmd lphdisk)
+	@$(call add,DEFAULT_SERVICES_ENABLE,apmd)

features.in/power/rootfs/image-scripts.d/50-power

+#!/bin/sh -efu
+
+# provide kernel interface for ACPI power button
+if [ -x /etc/init.d/acpid ]; then
+	grep -qsx button /etc/modules || echo button >> /etc/modules
+fi