Tips on remote debugging for filesystem code

[Julian Elischer]

On 24/8/17 1:40 pm, Aijaz Baig wrote:
> I am trying to understand the internals of the VFS/VNODE interface in the
> kernel and to that end I was attempting to go through the code flow. Hence
> I hooked up two FreeBSD VMs, one as the server and the second as the client
> using named pipes as serial ports.
>
> I put a breakpoint on say 'ufs_lookup' and I hit it by something as simple
> as doing an 'ls' over a directory. Then I try to step through the code and
> examine how the structures get populated and so on. However when I step
> through the code on (K)GDB after a few lines of C code, the server VM (the
> debugged machine) just kind of freezes while the client (on which GDB is
> run is also waiting on the server) and thereafter I always have to restart
> the server VM
>
> Am I doing something incorrectly? How do you guys normally do it? Keen to
> hear tips and best practices
>
I have had more success recently using BHype to make a Virtual FreeBSD 
machine

and connecting to it using the built-in gdb interface.


Firstly it is easier than a serial interface and secondly you don't 
need two machines.