[yocto] Best practice in debugging target software

[Pascal Bach]

Hello everybody

I'm currently trying to figure out the easiest way to debug an executable on a target.
What I ended up is the following approach:

1. Enable Debugfs generation using: `IMAGE_GEN_DEBUGFS = "1"`
2. Switch debug split style to: `PACKAGE_DEBUG_SPLIT_STYLE = "debug-file-directory"`

After building the image I end up with a rootfs and a rootfs-dbg

3. Extract both rootfs and rootfs-dbg somewhere (/home/projects)
4. Setup gdb with the following .gdbinit:

```
set sysroot /home/projects/rootfs
set debug-file-directory /home/projects/rootfs-dbg/usr/lib/debug
set substitute-path /usr/src/debug /home/projects/rootfs-dbg/usr/src/debug
```

With this setup I'm able to debug trough all libraries on the system.
So so far so good.

However for this to work I need to change the `PACKAGE_DEBUG_SPLIT_STYLE` to a non default and this made me wonder if I missed something.
- Is there a way to get this setup working with the default ".debug" style of OE?
- If not why is the .debug style the default instead of "debug-file-directory"?
- Is there any documentation? I was unable to find anything more than [1] in the Yocto Mega manual.
- Is there some best practice I missed?

Regards
Pascal

[1] http://www.yoctoproject.org/docs/latest/mega-manual/mega-manual.html#platdev-gdb-remotedebug-setup