Walther
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Re: Booting RaspPi - boot time, wake-on-lan

Fri Jan 27, 2012 10:43 am

Hey,

Just a simple question I couldn't find an answer for.

How long does it take to boot?

Of course, this depends on the speed of the class of the sd card, operating system of choice, etc small details, but I would like to get a rough estimate based on the current dev boards and the current default distro - a matter of seconds or closer to a minute?

Another question is Wake on Lan - I don't know much about it, but could that be used on RaspPi?

Regards,

V

Tomo2k
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Re: Booting RaspPi - boot time, wake-on-lan

Fri Jan 27, 2012 12:27 pm

The pre-release build on the Beta boards sold on Ebay took roughly 1 min 30 sec to get into a full LXDE windowed desktop in this video.

That version wasn't optimised for the hardware, it's a "this will boot almost any ARM" build.

So the real builds can be faster than that, and certainly considerably less if you don't need LXDE (eg to command-line or running your own program)

Wake-On-LAN almost certainly can't* exist because the RPi has no concept of being 'in standby' to wake up from. Plugged in it's on, unplugged it's off.

- It also draws less running all-out than many PCs do when 'off' (in standby)

*It might be possible to Wake-on-LAN back from the "safe to turn off computer" state if left powered, though that would need the LAN chip and USB stack to still be running so maybe not.

XAPBob
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Re: Booting RaspPi - boot time, wake-on-lan

Fri Jan 27, 2012 2:10 pm

No real NIC (USB based) so I imagine it's not possible.  But as has been pointed out there is no real point in going to "standby" because there is nothing really to turn off.

I could envisage a basic heartbeat based power trip could be programmed onto one of the IO pins, so if you don't take it high every 5 mins then power will be interrupted.  That would allow a minutely cron job to set it high for a second or two to be safe – if you kill the machine it reboots after 5 mins.

OTOH they aren't really meant to be inaccessible, so pulling the power should be an option.

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alexandru.cucu
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Re: Booting RaspPi - boot time, wake-on-lan

Mon Jan 30, 2012 2:48 pm

Right at this moment I am reading the documentation for the LAN9512 chip and there is "Wakeup packet support". Good thing I remembered this topic


The 10/100 Ethernet controller also supports numerous power management wakeup features, including “Magic Packet”, “Wake on LAN” and “Link Status Change”. These wakeup events can be programmed to initiate a USB remote wakeup.

The LAN9512/LAN9512i features three variations of USB suspend: SUSPEND0, SUSPEND1, and SUSPEND2. These modes allow the application to select the ideal balance of remote wakeup functionality and power consumption.


SUSPEND0: Supports GPIO, “Wake On LAN”, and “Magic Packet” remote wakeup events. This suspend state reduces power by stopping the clocks of the MAC and other internal modules.
SUSPEND1: Supports GPIO and “Link Status Change” for remote wakeup events. This suspend state consumes less power than SUSPEND0.
SUSPEND2: Supports only GPIO assertion for a remote wakeup event. This is the default suspend mode for the LAN9512/LAN9512i.


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kme
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Re: Booting RaspPi - boot time, wake-on-lan

Mon Jan 30, 2012 3:03 pm

Wake-on-LAN would make zero sense for R-Pi. You just leave on 24/7.

On a PC with an ATX PSU you can use WoL. This requires the PSU is on all the time and its idle loss is way higher than having a R-Pi at full throttle. And a R-Pi at idle? Half a lemon and a small plate of zinc and copper  will keep it running for a week (idle).

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alexandru.cucu
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Re: Booting RaspPi - boot time, wake-on-lan

Mon Jan 30, 2012 3:17 pm

If I understand it right from the documentation, it will only put the LAN chip in a low power state.

It would be useful if you would have to run the R-Pi from a battery and only need LAN to check or configure your system.

Imagine an automatic garden sprinkler system ran by the R-Pi. You could use the network to set the time when it should start watering your lawn. You can use a laptop for this so you don't run network cables to your house.

[edit]

You would say that if you have power for turning on and off the sprinklers you could also use it for the R-Pi... The R-Pi does not have a way to preserve time when off so if the power goes down and back up your sprinklers will start at the wrong moment
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hippy
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Re: Booting RaspPi - boot time, wake-on-lan

Mon Jan 30, 2012 3:54 pm

For PC-style WOL you need the NIC ( LAN interface ) powered and the SoC and other circuitry unpowered, the NIC sends a signal which in turn applies power to the rest.

If the NIC does indeed have a hardware signal to indicate receipt of a WOL packet that could potentially be done with the R-Pi but would involve some hardware hackery but that probably isn't easy. It's simply not designed with that in mind.

It would likely be much easier to have the SoC in a suspend or low power mode and wake from that if the SoC and OS supports it. Or do without as power consumption is far less than with most PC systems.

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