Some more tests:
- disabling LPAE has no effect, same hang after few minutes
- attempting to use 2GB MLO/u-boot on new 4GB board makes it very
unstable (crashes or hangs early while booting the kernel)

On Tue, Oct 2, 2018 at 6:29 PM Michael Mrozek
<EvilDragon@openpandora.org> wrote:
 ideas:
 - perhaps the problem has something to do with idle/power saving. Need
 to check if there are RAM registers related to that. Does anyone know
 if it currently tries to do RAM self-refresh while idle?

 Hm, but would idle / power saving trigger when the system is doing
 something?
 Because when doing my test runs, I always run a script that spits out
 the voltages, temperatures and remaining temperature left every 10
 seconds.

And what does it do in between those 10s? If the system has no work
for any periods, even as short as 1ms, it's called idle and power
saving mechanisms start.

 So Linux doesn't really idle around, but freezes anyways after some
 minutes.
 And sometimes it even freezes while booting - and it's anything but
 idle there.

It can be partially idle while booting, for example CPU can have
nothing to do while data is arriving from the SD card (data is copied
to RAM by SD card controller and CPU is not used). And because it is
some important data, like loading systemd itself, kernel would have no
other process to run and would put the CPU on idle for a short while.

 * See if a non-LPAE-Kernel has a different effect

no

 * Boot the kernel directly into a shell (without loading any other
   drivers except for the ones directly included in the kernel). Test
   whether this runs more stable and then modprobe the remaining drivers
   one after the other. After all, Tony was running the memtest similar
   as well, and that didn't fail.

Yeah that's something to try. Perhaps just move /lib/modules somewhere
so they don't autoload (not sure if they go to the ramdisk currently).

On Tue, Oct 2, 2018 at 8:54 PM H. Nikolaus Schaller <hns@goldelico.com> wrote:
 And I had a bad setup on one SD card some days ago for the LC15-eval board.
 This repeatably triggered a Freeze ca. 3 seconds into boot time (last
 messages were that LDO.8 and LDO.5 were initialized). The RESET button
 was responsive up to ca. 0.1 seconds before that, but not after.

I've seen such behavior too, it all just becomes super-unstable for no
reason, and it persists resets. I then have to remove the battery for
some time to recover, and then it comes back to hang-in-a-few-minutes
mode. This is without changing anything on the SD card. Really hard to
make any sense from all this.

Gražvydas

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