Messages in this thread |  | | Date | Fri, 22 Sep 2000 09:55:18 -0400 | Subject | Re: Hang on 2.2.17 - serial/tty related? | From | tytso@mit ... |
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From: Russell King <rmk@arm.linux.org.uk> Date: Wed, 20 Sep 2000 22:45:59 +0100 (BST)
I just experianced a complete hang of one of my systems here after using the serial port a lot (ie, open, read/write, close). I was using minicom, and I started to notice that each time I quit minicom, it would not exit.
ps alx revealed that it was waiting in tty_wait_until_sent, yet the serial port was not doing anything at all (I've got a couple of LEDs on the Tx and Rx lines). However, the port was in xon/xoff mode, but it seemed to be capable of transmitting immediately prior (note that at this time, the remote end had no capability to send an xon character to stop the transmission).
Can you define TTY_DEBUG_WAIT_UNTIL_SENT in tty_ioctl.c and RS_DEBUG_WAIT_UNTIL_SENT in serial.c and send me the results?
Also, which version of the serial driver are you using? The stock 2.2.17 or the one in serial.sourceforge.net?
When the actual crash happened, I changed the baud rate on the target system, and just changed the local baud rate to 115200. I then hit the enter key and that was game over. No response on network, nor X. The machine was completely and utterly dead to the point of requiring a hardware reset.
Hmm... my guess is that it may not be the baud rate changing, but the fact that the stty results in tty_wait_util_sent, and something is getting screwed up at that point. So if you could try to replicate the problem with the debugging statements defined, and then send the kernel log messages, that would be most useful.
Thanks!!
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