[microblaze-uclinux] Kernel Crash using second serial port

[Jeff McBride <mcbridejc@xxxxxxxxx>]

Hello All,

I am working on my first Microblaze application using uClinux, and I
have run into a problem. I am creating a relatively simple
application, to run on the Atmark-techno suzaku board, that reads
pulse widths for several incoming PWM signals (using custom VHDL
hardware) and that reads and writes data to a second UARTLite on
TTYS1. After initially thinking everything was working fine, I
discovered that the board will hang and stop responding after a random
period, usually somewhere between 2-15 minutes. I have seen a couple
of different error message printed to the console when it crashes. The
first is more frequent, but sometimes it gives the second message:

----------Error 1-----------
VFS: Insert <NULL> and press ENTER
kernel BUG at sched.c:562!

---------Error 2----------
Kernel panic: VFS: Unable to mount root fs on ff:fe
In idle task - not syncing

The basic flow of my application is:
1. read() call to poll serial port for incoming data, and when a full
message is received, process it (this basically means read a status
message and write to a mem addr to control an LED display)
2. Read PWM values (read mem addresses)
3. Write serial message with PWM values to ttyS1
4. usleep(20000)

My hunch is that this is being caused by the second serial port
somehow, because if I remove calls to the serial routines (read(),
write()), and just cycle the LEDS and do usleep() delays, it does not
crash. And if I remove the usleeps and serial write portions of the
application and just do repeated non-blocking reads, it crashes in
seconds.

Has anyone on the list encountered any similar problems, or does
anyone have any suggestions on where to look next?  I am somewhat
stumped at this point. I think my next step will be to figure out how
to get rid of the console on ttyS0 and use that for my application.

Thanks for any advice, I will be sure to send an update if I find a solution.

-Jeff

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