On my Samsung NC20 Netbook the BIOS hides the C3 C-state when the AC power is connected, but it should show up and work as soon as the AC power is disconnected.
This expected behavior worked fine as long as I used Oneiric. But now I upgraded to Precise and now C3 does not work anymore after disconnecting the AC power.
I have verified, that booting the Oneiric kernel 3.0.0-19.33 instead of the Precise Kernel 3.2.0-24.37 (same userspace) fixes the problem.
To gather some information, I executed this command with the Precise kernel
grep -r "" /sys/devices/system/cpu/cpu0/cpuidle/
in different system states:
1. newly booted without having the AC power attached
2. having the AC power attached (without C3, as expected)
3. now after having the AC power disconnected (not functional C3 --> bug)
The output is combined in the attached file "cpuidle.txt".
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices:
**** List of PLAYBACK Hardware Devices ****
card 0: VT82xx [HDA VIA VT82xx], device 0: ALC272 Analog [ALC272 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
ApportVersion: 2.0.1-0ubuntu7
Architecture: i386
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: VT82xx [HDA VIA VT82xx], device 0: ALC272 Analog [ALC272 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: schlicht 2920 F.... kded4
schlicht 3190 F.... kmix
Card0.Amixer.info:
Card hw:0 'VT82xx'/'HDA VIA VT82xx at 0xf5400000 irq 67'
Mixer name : 'Realtek ALC272'
Components : 'HDA:10ec0272,144dc04e,00100001'
Controls : 18
Simple ctrls : 10
DistroRelease: Ubuntu 12.04
HibernationDevice: RESUME=/dev/sda6
MachineType: SAMSUNG ELECTRONICS CO., LTD. NC20/NB20
Package: linux 3.2.0.24.26
PackageArchitecture: i386
ProcEnviron:
LANGUAGE=de_DE
TERM=xterm
LANG=de_DE.UTF-8
SHELL=/bin/bash
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-24-generic-pae root=UUID=28a00041-0781-44a2-8a24-684926bf9ea9 ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic-pae 3.2.14
RelatedPackageVersions:
linux-restricted-modules-3.2.0-24-generic-pae N/A
linux-backports-modules-3.2.0-24-generic-pae N/A
linux-firmware 1.79
Tags: precise
Uname: Linux 3.2.0-24-generic-pae i686
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
dmi.bios.date: 11/25/2009
dmi.bios.vendor: Phoenix Technologies Ltd.
dmi.bios.version: 10MQ
dmi.board.name: NC20/NB20
dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvr10MQ:bd11/25/2009:svnSAMSUNGELECTRONICSCO.,LTD.:pnNC20/NB20:pvr04MQ:rvnSAMSUNGELECTRONICSCO.,LTD.:rnNC20/NB20:rvr:cvnSAMSUNGELECTRONICSCO.,LTD.:ct10:cvrN/A:
dmi.product.name: NC20/NB20
dmi.product.version: 04MQ
dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD.
apport information