kgdb debug with ttyUSB0 instead of ttyS0

[Oliver Graute]

On 26/04/17, Greg KH wrote:
> 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 :)

ok that make sense

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

thats not so easy. Even the old notebooks today lacks a "real" serial
connection. Perhaps I should use a raspberry as target. There I can get
a serial over the gpios.

Best Regards,

Oliver