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Date: Mon, 10 Sep 2012 19:30:37 -0500 (CDT)
From: Robert Bonomi <bonomi@mail.r-bonomi.com>
Message-Id: <201209110030.q8B0Ub0G083363@mail.r-bonomi.com>
To: freebsd-questions@freebsd.org
Subject: Where are the mechancs of config(8) descibed
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(This is probably a bit techical for 'questions' -- I'd welcome a suggesstion
of a more appopriae forum.)

Is there a detailed description anywhere of the mechanics of *how* config(8) 
does what it doess?

I'm looking fo the gory detail of how, sayi, 'device bpf' causes the
creation of the file 'opt_bpf.h' containing '#define DEV_BPF 1"

_Part_ of the magic is the sys/conf/files* and sys/conf/options* files,
but their format/content isn't defined anywhee I've found.


rerason for asking -- I want to addd a cutom device driver into the
kernel.  I have sources, and can build the .o,   if i convert it to
a .ko, it loads and run.  *BUT* I want to embed it in the kernel at
build time.

"Somewhere", I have do define 'device foo', specify that that name
adds 'myfoo_sys.o' to the kernel object-files list, and that 
myfoo_sys.o depends on a list of source files, and requires a 
particular sequence of commands to build from those shources.

I know the 'what', just not the 'where' or 'how'.

Any pointers appreciated.