Date: Tue, 19 Apr 2016 22:05:55 +0530 From: Aijaz Baig <aijazbaig1@gmail.com> To: cem@freebsd.org Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>, freebsd-stable@freebsd.org Subject: Re: Toggling between remote KGDB and local DDB within a debugging session Message-ID: <CAHB2L%2BfKTSDk-Ke6UWubE_X4gaxaHLULgWKu_Je8tNUddht5tw@mail.gmail.com> In-Reply-To: <CAG6CVpV_P2eCERSjQ3cwAMvNkuO8d919Td3DxkQJR1SGHSvLag@mail.gmail.com> References: <CAHB2L%2Bde=Bxn4G2uEDdN%2BSPY=SREN9REGShV=gnRombjqStYzw@mail.gmail.com> <CAG6CVpV_P2eCERSjQ3cwAMvNkuO8d919Td3DxkQJR1SGHSvLag@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, Apr 19, 2016 at 9:08 PM, Conrad Meyer <cem@freebsd.org> wrote: > On Tue, Apr 19, 2016 at 5:49 AM, Aijaz Baig <aijazbaig1@gmail.com> wrote: >> I would like to know if there is indeed a way to toggle between gdb >> and ddb while debugging a remote kernel. I am already at the gdb (or >> rather kgdb) prompt. From here how do I switch to local ddb on the >> debugged machine?? > > Ctrl-c on the serial console. For me I merely see 'Quit' being spat out when I do a ctrl-c > >> When remote remote KGDB is listening and I force a >> panic using 'sysctl debug.kdb.enter=1', it drops into remote KGDB. >> However, when it is NOT listening on the serial port, the local system >> just freezes > > Are you sure ddb just doesn't run on the serial port? For the very first time, a manual panic does indeed bring up the ddb prompt. However it is only AFTER I've attached kgdb to it, does this start happening, namely not going back ever to ddb (with 'Quit' being displayed instead and with the control still with KGDB) > >> What I want, is to enter ddb on the local machine. Do some debugging >> using it; drop to remote KGDB for things that are best done using >> KGDB, then switch back to local DDB when I'm done. > > Yes. I regularly do this with ctrl-c (gdb->ddb) / "gdb" (ddb->gdb). If it'd help, I'm using VMs. So my serial console is actually the VM console. Now just to be on the safe side I tried putting "comconsole" into '/boot/loader.conf'. However now, with the aforementioned sysctl, it doesn't drop to ddb even for the very first time unlike previous trials where. dropping into DDB was smooth as long as KGDB was not attached to it ever. > > Best, > Conrad Keen to hear from you -- Best Regards, Aijaz Baig
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAHB2L%2BfKTSDk-Ke6UWubE_X4gaxaHLULgWKu_Je8tNUddht5tw>