In nouveau_pm.c, in the function nouveau_pm_acpi_event(), there's no check for CONFIG_POWER_SUPPLY. If CONFIG_POWER_SUPPLY is set to either n or m, the power_supply_is_system_supplied() is 'missing' and there's a build error. One solution is to add an #ifdef CONFIG_POWER_SUPPLY along with the #ifdef CONFIG_ACPI before the function. -- Stratos Psomadakis