On Wed, Apr 26, 2017 at 01:23:55PM +0200, Oliver Graute wrote:
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.
Why do you need to use a notebook where Linux works already for kgdb? That's traditionally only used to bring up new hardware platforms. Also, there is USB serial debugging cables as there is a special mode in the USB 2 and 3 controllers that can be enabled to handle serial messages without interrupts for console/printk early messages that people use. The cables are not cheap to enable this, but worth it if you have to debug this type of target system. Good luck! greg k-h