Hang while "Switching to gdb back-end"

[Arka Sharma]

Thanks for the reply. I have one more silly question. I have a terminal at
ttyu1 and I can login through telnet and it works fine except when I issue
"sysctl debug.kdb.enter=1" it hangs showing "debug.kdb.enter". I have
checked the freebsd handbook. At it is mentioned in chapter 26.6, I tried
to put "device sio" in my Kern Conf and it gives me build failure. Looking
at the build log it seems it is missing some header file while building
dev/sio.c. Basically I tried to get into db from serial console and failed.
One more thing is in the console after I get into db and launched gdb I
have also tried connecting kgdb from another host, but got timeout while
connecting the target.

Regards,
Arka

On Thu, 2 Jul 2020, 22:08 Navdeep Parhar, <nparhar at gmail.com> wrote:

> On Thu, Jul 02, 2020 at 05:57:58PM +0530, Arka Sharma wrote:
> > Dear All,
> >
> > I have installed FreeBSD 12.1. I have set the "hint.uart.0.flags="0x90"
> in
> > the /boot/device.hints file. I also have both ddb and gdb listed when I
> > issue "sysctl   debug.kdb.available".  So when I launch db using "sysctl
> > debug.kdb.enter=1" and issue gdb to change the mode to gdb it shows
> > "Switching to gdb back-end" and doesn't respond to Ctrl+c. I have to
> reset
> > the system in order to get the system up.
>
> All this is expected behavior.  You have to connect to the gdb backend
> over the serial port using kgdb running on a different system after you
> see the "Switching to gdb ..." message.  Then debug as usual and detach
> when done.
>
> Regards,
> Navdeep
>