Suspend to disk? SD-HD

marc zonzon marc.zonzon at gmail.com
Tue Jun 8 11:58:03 EDT 2010


2010/6/7 Rubén Berenguel <ruben at mostlymaths.net>:
> Hi eveyrone,
>
> I have one small question. Has anyone tried setting up "suspend to
> disk" with a microSD? If not, I'll try it tonight/this week (today I'm
> buying a microSD for swap). If suspend to disk means quicker
> powerup... welcome it is! As the nano stands now, it can live all day
> with the battery charged... but it is pointless for it to be all day
> idle (suspend to ram) when I am not really using it. I use usually in
> short bursts, I can wait 5 seconds or so for it to power up if needed
> if the battery life gets extended.
>
> As a side note, yesterday before falling asleep I had an idea, maybe
> for the Ya, maybe not. I'm no engineer. But, "what if" the hard disk
> of the Ya (or of a Ben2) was an (micro)SD card? Go back 20 years, when
> there were no hard disks and we used disks to load the system... more
> or less. I see a few pro's, but don't know what the cons may be.
>
> Pro:
>
> Hard switching operating systems: you can have openwrt in one card,
> debian in another.
> No disk failure problems: a disk fails, well, buy another
> Bigger: the "ben2" could ship with the smalles possible (256mb? 512
> mb? even 128 if they still sell!)  but could be upgraded to... say,
> 16gb (I've seen microSD that big, not cheap though).
>
> The card could be placed like SIM cards are in a phone, in a sliding
> compartment below the battery, even, not needing "outer space" to put
> it in (and avoid risking removing it)
>
> Cons:
>
> I don't know, really. I guess there should be some?
>
> Ruben
>


I have also looked for a way to suspend to flash (SD or mtd) but I
didn't find anything easy.
The pm-suspend or the hibernate script only suspend to ram (I don't
know how different they are for that).
But when you want to suspend to disk I know about three methods:
- Tuxonice patch: I don't know if it exists for mipsel and how it is
compatible with openwrt+qi patches;
- uswsusp: On Debian it does not exist for mipsel, and I don't know if
it compiles on mips architecture, -
- sysfs method: with the openwrt-qi kernel I get  'mem' as value of
`cat /sys/power/state`. I means that syfs can suspend to ram, but not
disk. Can we enable that in the kernel?

In any case when trying the script 'hibernate-disk' I get 'No suitable
suspend methods were found on your machine.', so when I use hibernate
it falls back on hibernate-ram

Rubén do you get a different result? Have you got disk suspend?

Do somebody see an easy way to implement suspend to disk (flash in
fact), patching the kernel is OK, but I have not the time to debug
never applied patch!

I would be also interested in knowing how log a Nano can stand in
suspend to ram, and what is the gain of suspend to ram. To put the lcd
we don't need suspend to ram, do the processor still draw energy while
suspended to ram or only the ram? I suppose ay QI you have done
measure on what is needed for each component.

Marc




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