Hi Jason,

On Thu, Jan 31, 2013 at 05:19:32PM -0700, Jason Gunthorpe wrote:

On Thu, Jan 31, 2013 at 07:01:09PM -0500, Jason Cooper wrote:

quoted

If you're interested, I still have a few ideas.  One was to wire two USB
serial adapters end to end to create a different console
(console=/dev/ttyUSB0,115200, getty, etc).  Since they would be going
over usb, that's a different clock, so it should work and provide us
with a safety net.

I can't recall, can you still use JTAG once the CPU has hung on a mbus
access?

If so memory dumping the console ring, or cpu registers would get the
answer pretty directly..

My guesses would be the RTC and/or GPIO blocks (the GPIO blinker needs
a clock), based on table 94.

These guesses seem to be dead on:

Moved the RTC module and GPIO modules (keys, leds) out of the way, to
see whether they cause the boot with disabled runit to lock up.

System boots now and SSH login is possible!

# mount -t debugfs debugfs /sys/kernel/debug 
# cat /sys/kernel/debug/clk/tclk/runit/clk_enable_count 
0
# insmod ./gpio_keys.ko 

System locks up.

and, after a reboot:

# insmod ./rtc-mv.ko 

System locks up.

Bingo!


- Simon