Re: Linux stuck when serial cable is disconnected
On Sat, Oct 20, 2007 at 10:09:37AM -0700, hagit wrote:
> I am running on a MIPS machine, with my kernel and debian distribution
> (file system).
> The kernel messages are configured to get out from the serial
> connection, i.e. serial console.
> When the serial output of my MIPS is connected to my PC everything is
> OK and I can see the outputs in the terminal.
> When I disconnect the serial cable my Linux get stuck. Even my telnet
> connection doesnt responds.
> When I re-connect the serial everything is OK again.
> Do you know what can be the problem?
> I am working with HW flow control? can it be the problem?
Sure. HW is telling the serial port that the kernel thinks is its
console that it is not Clear To Send; so it waits. Do you have another
device that could also be a console? I.e. on a normal i386 with both a
VGA console and a serial console, the console messages will go to both.
If the serial is disconnected, the kernel can still send to the VGA.
I don't know MIPS to know what other console options there are.
I could be wrong and its not hardware flow-control (RTS/CTS) that's the
problem but things like DSR and DTR. You could try tying DSR and DTR
together at the cable end so that it gets its own signal.
Or, I could be totally wrong and the kernel should be able to send to
the console serial port even if nothing is connected.
Doug.
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