Glorious CCCG thread -- Cellphone Compute Cluster for GIMPS

[ewmayer]

OK, so in preparation for scouring the scrap piles in various places, we need the following (in the "general agreement on this" sense):

o An itemized list of the needed minimal hardware (and software, if relevant) configuration. Detailed model-numbers known to use ARMv8 CPUs for the major brands would be useful in this regard.

o A how-to-check-if-a-given-discard-phone-actually-meets-the-criteria: So I'm at the local repair shop with my laptop, which I connect to a candidate phone via USB-to-USB-C cable. How do I access the phone hw/sw configuration information? Is working-hardware-but-corrupted-OS a scenario needing to be dealt with here, and if so, how to handle it?

o Some kind of quasi-standardized "other supporting hardware and software" list. On the hw side, do we need cheap 8GB microSD cards flashed with a common kernel? What are good low-cost (and low-power-wastage) options for distributing power to a farm of 10 or more such devices?

I can collate and maintain said how-to short-lists as an attachment to the OP, i.e. in a place convenient for viewers of the thread.

[kriesel]

Here's a list of a few that are not ARM based

https://www.quora.com/Do-all-mobile-...x86-processors

Possibly bring donuts or other treat for the phone store technician in exchange for resetting the phone(s) to factory (previous customer password, phonebook, etc erased, for those that can't be reset/unlocked by customer)

[M344587487]

My 2 cents:

Originally Posted by ewmayer

...
o An itemized list of the needed minimal hardware (and software, if relevant) configuration. Detailed model-numbers known to use ARMv8 CPUs for the major brands would be useful in this regard.
...

Snapdragon 808 SoC and up with ARM and/or Kryo cores. Exynos 7420 SoC and up except for the 7580 (because it's 28nm) with ARM and/or Mongoose cores (M1, M2, M3, M4). Most of the off-brand phones I've seen have had much weaker cores. Some of the latest models have three core clusters which should be very interesting in a few years.

Originally Posted by ewmayer

...
o A how-to-check-if-a-given-discard-phone-actually-meets-the-criteria: So I'm at the local repair shop with my laptop, which I connect to a candidate phone via USB-to-USB-C cable. How do I access the phone hw/sw configuration information? Is working-hardware-but-corrupted-OS a scenario needing to be dealt with here, and if so, how to handle it?
...

Search online for the model, you'll find the SoC in no time. There's usually a factory reset which may fix a corrupted OS, which is probably the first thing a repair shop will have tried.

Originally Posted by ewmayer

...
o Some kind of quasi-standardized "other supporting hardware and software" list. On the hw side, do we need cheap 8GB microSD cards flashed with a common kernel? What are good low-cost (and low-power-wastage) options for distributing power to a farm of 10 or more such devices?
...

A USB adapter so you can plug a mouse and keyboard in for if touch is broken. Most repairable phones have smashed screens ranging from no LCD damage to glitchy or dead spots to fully dead. You can get USB to HDMI adapters for external display output but I haven't tried them, you may need to initiate it on the phone which could be a problem if touch is dead. With only one USB interface it may be a PITA if both screen and touch doesn't work, bluetooth mouse and keyboard may be an option if you can somehow get them to pair. A lot of phones don't have a microSD slot, totally dependent on internal memory. I doubt there is one kernel to rule them all.

[M344587487]

Updated with phones from Google, HTC and LG. I'm inclined to remove the Snapdragon 808 from the list because it seems too weak to bother with, thoughts?

[ewmayer]

Originally Posted by M344587487

Updated with phones from Google, HTC and LG. I'm inclined to remove the Snapdragon 808 from the list because it seems too weak to bother with, thoughts?

Thanks, that tabulation is very helpful! If I read your table right, the 808 has both a dual-core A57 and quad-A53. By way of comparison, my Odroid-C2 has just a 4xA53 and I'm running DCs on it, at the pokey-but-steady rate of about 1 every 2 months. I would consider that to be around the bottom end of what is useful. So it depends on what the clocking and mem-speed of the cores in the 808 are.

With regard to that - this week I'm gonna hit the local repair shop and see if I can score just 1 no-longer-usable-as-phone-but-OK-as-compute-node phone from your list to use as a sort of guinea pig. Pardon the n00b questions, but how do I load software (in my case an Mlucas binary) onto it and run it? (E.g. how do I access the filesystem, etc.) Can such a binary compiled for ARM/Linux run under Android, or will I need to build under the latter? If so, are the needed compile tools included in the standard OS install, or will I need to install a developer toolkit?

[masser]

I may have an iPhone 5S to donate to the cause. Is it too old? Would any one be able to provide a link to instructions for wiping all personal data from a phone?

[M344587487]

Originally Posted by ewmayer

...
Pardon the n00b questions, but how do I load software (in my case an Mlucas binary) onto it and run it? (E.g. how do I access the filesystem, etc.) Can such a binary compiled for ARM/Linux run under Android, or will I need to build under the latter? If so, are the needed compile tools included in the standard OS install, or will I need to install a developer toolkit?

I don't know the best way to go about running mlucas, I believe you can run ELF binaries if you root the phone but have never rooted mine as I was concerned about bricking it. Once rooted I believe you have pretty much full Linux admin access, gcc included AFAIK. It's possible that the c2 build you did would just work which would be pretty neat, otherwise building on the device will work as long as the seg fault issue that seems common to many ARM devices doesn't show up. The other possibility is using the android studio + SDK to compile mlucas into an APK. As I understand it you'd use the NDK to compile mlucas into a library, then have a simple java wrapper call that library through the JNI. No success yet but I barely swore at all so couldn't have tried too hard. An APK would be a last resort as there's probably gotchas baked in.

Originally Posted by ewmayer

Thanks, that tabulation is very helpful! If I read your table right, the 808 has both a dual-core A57 and quad-A53. By way of comparison, my Odroid-C2 has just a 4xA53 and I'm running DCs on it, at the pokey-but-steady rate of about 1 every 2 months. I would consider that to be around the bottom end of what is useful. So it depends on what the clocking and mem-speed of the cores in the 808 are.

I don't know how much stock to put in the paper clockspeeds, they may only apply under ideal conditions such as the other cluster being idle. I could also be being too idealistic in saying only 20nm and better processes are viable, the pi3 may be as old as 40nm and it looks like the c2 is 28nm. Hopefully the newer processes go a long way to making an ARM cluster efficient enough to trade blows with x86, eager to test that out.

Originally Posted by ewmayer

With regard to that - this week I'm gonna hit the local repair shop and see if I can score just 1 no-longer-usable-as-phone-but-OK-as-compute-node phone from your list to use as a sort of guinea pig.

I've ordered a few broken phones which should get here in a week, if they can be resurrected some of the questions can be answered. Race you :P

[ewmayer]

The Android-phone jack-of-all-trades at the local wireless store said that to the best of his knowledge the idea of using a broken/missing-screen phone core for computing wouldn;t work because using the micro-USB connection requires explicit user permission via the touchscreen interface. True or false?

[Mark Rose]

Originally Posted by ewmayer

The Android-phone jack-of-all-trades at the local wireless store said that to the best of his knowledge the idea of using a broken/missing-screen phone core for computing wouldn;t work because using the micro-USB connection requires explicit user permission via the touchscreen interface. True or false?

That's the situation with the three Android phones I have from Android 4 through 9. Basically you need to enable USB debugging. But if the screen is somewhat legible, that should be enough.

[retina]

Originally Posted by ewmayer

The Android-phone jack-of-all-trades at the local wireless store said that to the best of his knowledge the idea of using a broken/missing-screen phone core for computing wouldn;t work because using the micro-USB connection requires explicit user permission via the touchscreen interface. True or false?

That's why you need to root it or reflash it. Don't use the existing OS, it will get in your way and annoy you. Plus it will try to talk to google and just generally do lots of stuff that kills your throughput.

[Mark Rose]

Originally Posted by retina

That's why you need to root it or reflash it. Don't use the existing OS, it will get in your way and annoy you. Plus it will try to talk to google and just generally do lots of stuff that kills your throughput.

How do you reflash it without enabling USB debugging?