kgdb debug with ttyUSB0 instead of ttyS0

[Greg KH]

On Tue, Apr 25, 2017 at 11:11:38PM +0200, Oliver Graute wrote:
> Hello list,
> 
> i'am using a null modem cable with two usb to serial converts on both
> ends between my develop and my target machine. The connection is fine.
> On both machines the serial interface is /dev/ttyUSB0 for this connection.
> 
> On the target machine I try to enable kgdboc
> 
> echo ttyUSB0 > /sys/module/kgdboc/parameters/kgdboc
> 
> but only got:
> 
> echo write error: No such device
> 
> if I try:
> 
> echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc
> 
> is not complaining. Some ideas why ttyUSB0 can't be used with kgdb?

USB needs interrupts in order to run properly, which kgdb doesn't enable
when you stop the target, for obvious reasons :)

Stick to a "real" serial connection and you should be fine.

good luck!

greg k-h