Re: Issues using KGDB on a Linux machine to debug NetBSD

[Eduardo Horvath <eeh%NetBSD.org@localhost>]

On Fri, 8 Jun 2012, Israel Jacquez wrote:

> Hello,
> 
> I'll make this short. I can't seem to get debugging support working
> even when following the guide:
> <http://www.netbsd.org/docs/kernel/kgdb.html>.
> 
> Target: NetBSD 5.1.2 on the i386 port
> Remote: Debian GNU/Linux
> Kernel on target: NetBSD-CURRENT
> 
> I have enabled the following options in the kernel config file:
> 
> options DDB
> options DDB_HISTORY_SIZE=512
> options KGDB
> options "KGDB_DEVNAME=\"com\"",KGDB_DEVADDR=0x3f8,KGDB_DEVRATE=115200
> makeoptions DEBUG="-g"
> 
> After compiling the kernel on the remote machine (Debian GNU/Linux), I
> copy the new kernel to / on the target machine and I see:
> 
> When I invoke dmesg(8): dmesg | grep -E '^com', I get the following:
> com0 at isa0 port 0x3f8-0x3ff irq 4: ns16550a, working fifo
> com0: console
> com0: kgdb
> 
> I then reboot and at the boot loader, I invoke:
> boot -d
> 
> Immediately, I get dropped into DDB. I can only see this through the
> serial console as the target machine is running headless. After, I

If you have both DDB and KGDB enabled you need to give DDB a specific 
command to drop into KGDB.  Only then can you connect the remote gdb.

Eduardo