Re: netgraph: documentation issue? What kernel options? Where to find?

On Sun, 2017-07-16 at 22:48 +0200, O. Hartmann wrote:
> For a small SoC based system, I use a highly customised static kernel
> and build the
> system via NanoBSD with no kernel modules.
> 
> Tyring to track down some network issues with recent CURRENT I
> figured out, that when
> using the ppp client to connect via modem to the ISP and there is no 
> 
> options	NETGRAPH_ETHER
> options	NETGRAPH_PPPOE
> 
> in the kernel configuration, the resulting system fails to establish
> a ppp session. The
> man page states, that a netgraph node is established, but as hard as
> I look, I can not
> find any(!) information in the man pages what options are
> necessary/optional to provide
> the correct module statically.
> 
> The same is for many other NETGRAPH_XXX features. Starting from man
> page "man 4
> netgraph", section "SEE ALSO", I started tweaking the kernel with
> NETGRAPH_XXX, i.e.
> ng_vlan -> NETGRAPH_VLAN until the compiler bails out with an error,
> for instance
> ng_car -> NETGRAPH_CAR.
> 
> I tried to find out what options cover which netgraph module but
> there is - right,
> nothing I can find on a direct route.
> 
> Since netgraph isn't so brand new (I guess ~ 2000 from the PDFs I
> found on the network),
> there must be some documentation other than "reading the source
> code".
> 
> Please give me some hints where to find the entry point for the
> appropriate documented
> options for netgraph modules.
> 
> Obviously, some ng_xxx modules are prerequisite for some services to
> work properly, as
> ppp - but I can't find any hints for "options NETGRAPH_ETHER" or
> "options NETGRAPH_PPPOE"
> in the manpages (looked at ppp, pppoed). 
> 
> Thanks in advance,
> kind regards
> 
> Oliver
> 

I can't help with anything specific to netgraph or its [lack of] docs.

For the general question "How do I know what undocumented device or
option statement to put in my kernel config to get xxxxx" a good place
to start is /usr/src/sys/conf/NOTES.  It's supposed to contain all the
options and devices (except some machine/arch-specific stuff).  If you
don't find it in NOTES, try "grep -i xxxxx *" in that dir, you may find
the thing you're looking for in 'options' or 'files' and get some clues
that way.

For the netgraph stuff, I see that in NOTES it tells you how to find
the manpages for netgraph things, so I guess I accidentally did answer
that part too.  :)

-- Ian