Re: Arm v7 RPi2 -current unresponsive to debugger escape during buildworld

Once again a Pi2B has become unresponsive during buildworld. The top display
reports in part:
....
last pid: 73771;  load averages:    3.03,    2.90,    2.86                  up 1+22:36:46  07:53:47
44 processes:  4 running, 40 sleeping
CPU: 74.9% user,  0.0% nice,  0.8% system,  0.2% interrupt, 24.1% idle
Mem: 310M Active, 55M Inact, 7356K Laundry, 175M Wired, 98M Buf, 365M Free
Swap: 1770M Total, 106M Used, 1664M Free, 5% Inuse
Jan 13 20:02:04 generic syslogd: last message repeated 1 times
  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
73771 root          1 141    0   311M   229M CPU2     2   3:27  99.89% c++
73767 root          1 141    0   243M   160M CPU1     1   7:51  99.88% c++
73747 root          1 141    0   328M   180M CPU3     3  17:27  99.86% c++
70665 root          1   0    0  6868K  1712K CPU0     0   6:45   0.73% top
 3995 ntpd          1   0    0    14M  1700K select   0   1:41   0.06% ntpd
 3378 root          1   0    0    13M  3372K select   0   0:06   0.02% wpa_supplicant
64335 root          1  27
....
There's no visible updating taking place, the timestamp is three hours slow.
Typing in the console window isn't echoed, issuing q to quit top has no
effect.

However, there's an oscilloscope connected to the transmit pin on the
serial console wiring, and it's getting traffic every two seconds. The
output is very brief, 20-50 ms.

Killing and restarting the terminal emulator, called "serial port terminal"
on the RasPiOS host serving as console, reveals the FreeBSD buildworld is
still running and generating output. Switching to cu as the terminal emulator
confirms that the buildworld process is still running and making progress.

So, the Pi running FreeBSD isn't the problem, at least not now. Other
instances that didn't involve a direct usb-serial connection from RasPiOS
to a FreeBSD host and wouldn't respond to the debugger escape used tip to
make the serial connection between two FreeBSD hosts. I didn't try restarting
tip. It looks like that's the next test to try.

Thanks for reading what looks like an extremely long goose chase!

bob prohaska