Discussion

WOL support

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bpiuser  
Hello,

really great work - thanx a lot for the good work !

For my applications that need remote power on/off I would love to have WOL (wake on LAN) feature.

So far I understand from other threads here, that WOL is not implemented so far, which I confirmed via ethtool eth0.
Wake-on: d feature missing.

As WOL should be possible from A20 / RGMII hardware side (right?) - could you please check your plans to add WOL to the eth0 driver. You prob. may look this up from the RPI drivers, which doi have WOL support.

This WOL would be highly appreciated.

Thanx in advance.
Totally second that

I doubt that this design could handle WOL in reasonable way.

Since power consumption is pretty low, why would you like to have WOL at all? My system starts early in the morning and runs the whole day until I switch it off together with Internet router etc. when I go to bed...

bpiuser  
WOL is the only way to wake up the BPi via remote software without local user action
When services provided by BPi are not needed I want to swith it off and wake it again, when needed,
This request is not mainly derived from potential power savings though.
On RPi this seems to be possible, but I need SATA ....

tkaiser  
Edited by tkaiser at Tue Dec 9, 2014 10:12
bpiuser replied at Tue Dec 9, 2014 09:53
WOL is the only way to wake up the BPi via remote software without local user action


WOL could only work if a) the part of the BPi implementing the MAC part of the network interface would be on (and this is the A20 SoC itself -- something has to permanently listen on the interface for the appearance of the specific 'magic packet') and b) when there would be something able to switch 'the computer' on after the 'WOL processor' received the magic packet. So basically you're asking for the A20 being shut on permanently to listen for WOL requests to do what afterwards?

And while you might switch on your BPi remotely using different approaches they all have in common to consume more power compared to the BPi idling around.

bpiuser  
thanx for the hint
implementations I am aware of support WOL not via CPU rather than via WOL aware NIC - just recognized that RPi has WOL capability...  
if this hardware is not implemented then WOL does not make any sense indeed.
just downloaded the A20 manual to better understand underlying BPi architecture esp. the limitation with the CBS SATA switching rather that FIS found in the other thrad.
Any further docu you would recommend reading ... ?  

tkaiser  
Edited by tkaiser at Tue Dec 9, 2014 13:29
bpiuser replied at Tue Dec 9, 2014 13:04
thanx for the hint
implementations I am aware of support WOL not via CPU rather than via WOL aware N ...


There is no NIC on the board that might support that feature (and consume way more power than a BPi idling around). The MAC part of the NIC lives inside the CPU and the PHY is implemented as an el cheapo RTL8211. If the BPI is off then everything's off (exactly the same applies to the RPi that is also not able to implement WOL. The NIC on the RPi is part of an USB hub which is also off, so while ethtool or the driver in question might tell you lies the hardware is not able to make WOL possible).

There's not much you can read there expect of the ACPI specs (this is where WOL comes from: keeping a PC in a state where it just consumes 2-5 times more than a BPi to be able to react on magic packets to be 'soft powered on' again: G2/S5 state). ACPI on ARM might make some sense here and there. But that doesn't apply to WOL or the ACPI power states.

If you manage to clock the BPi down when nothing's to do for longer times and let unused peripherals like disks sleep then I would assume this would consume less power compared to nearly all other 'remote switch' solutions for this energy efficient platform.

bpiuser  
thanx for the comprehensive answer ... still looking around for more hardware docu though...

the down clocking looks promising - will give it a try - good point.

Just as a side note concerning power figures: My fully fledged Intel Haswell based NAS OMV-NAS with 3 x 4TB Red + mSATA boot disk consumes <12Watts idle (disks spun down) and ~0.3Watts in shutdown/WOL mode, waiting for the the next WOL command to start booting.
But there are other scenarios where WOL would be nice - e.g. if you have ever pressed the power off button on the XBMC remote ;-)

tkaiser  
bpiuser replied at Tue Dec 9, 2014 16:43
thanx for the comprehensive answer ... still looking around for more hardware docu though...

the do ...

If you don't find documentation starting from here on I doubt you're lost: http://linux-sunxi.org/A20#Documentation

Regarding typical standby/WOL power consumption you're right. In the last years it was possible to implement the feature with a modern PSU with separate standby 5V rail and additional WOL circuitry on board that assist the NIC's SoC/ASIC: https://www.silabs.com/products/mcu/Pages/Wake-on-LAN.aspx

Just a decade ago typical PCs with an ATX PSU consumed a few watts even when totally 'off' (not even standby/WOL).

And if a remote shutdown by accident through an app is a problem I would search for a way to disable this feature on the XBMC host.

BTW: In a few weeks I will continue with some tests/measurements in the 'servers/network' forum regarding also low power consumption (clocking down based on average load, deactivating power for SATA drives/LCDs, comparing external consumption -- between PSU and wall -- and internal measured by the Banana Pi's power management unit AXP209)

I did some search too.
What tkaiser is perfectly true : I did a test with a ATX PSU from a cannibalized IBM/Lovono and it consume about 15w in "sleeping mode" as per my UPS. About 3 time the consumption of my bPI + its SATA drive.

My only problem is I duno how to remotely wake up the beast.
I mean, if you power you bPI with some solar panel, the MPU will shutdown the system when the voltage become to low. But when the sun raise back, I didn't find a way to restart the system ... as I can do with a PIC.

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