Re: kern/57564 raspberry pi zero W also panic in linux (tried cpu freq reduction)

[Ramiro Aceves <ea1abz%gmail.com@localhost>]

Hello,

I have been investigating crashes under raspbian Debian GNU/Linux for 
several days and found in internet that Raspberrypi Zero W frequently 
panices with CPU max frequency set to 1 GHz.

As I told before, I have got crashes after several hours of the CVS and 
rm -rf pkgsrc torture test in such conditions.

I found internet articles that suggested reducing max CPU frequency from 
1 GHz to the next scaling step, 900 MHz. After doing that, I have run 
the test for 3 days and no panics at all. At the end, SD card showed a 
problem and system went suddenly read only. I copied the SD into a file 
for further investigation.

After that, I started to burn NetBSD 10 beta on the SD card but it 
refused to be written. SD card was dead, I could not flash it with any 
computer at home.

I have just bought a new card, this time 64 GB size (last one was 16GB). 
I have flashed my NetBSD 10 beta copy from the backups with the custom 
kernel with Taylor modification. It automagically resized to the full 64 
GB of the card at the first boot.

It showed the following CPU available frequencies. I do not know why but 
900 MHz is not available:

machdep.cpu.frequency.available = 700 1000

So I set in /etc/rc.local:

sysctl -w machdep.cpu.frequency.target=700

Now raspberrypi Zero W is running at 700 MHz:

sysctl -w machdep.cpu.frequency.target=700
raspa-netbsd$ sysctl -a | grep freq
machdep.cpu.frequency.target = 700
machdep.cpu.frequency.current = 700
machdep.cpu.frequency.min = 700
machdep.cpu.frequency.max = 1000
machdep.cpu.frequency.available = 700 1000

I am running the CVS/rm torture test. We'll see what happens.

Regards.
Ramiro.