basic driver build environment

[M. Warner Losh]

In message: <20050917173941.GJ6440 at eyore.cobbled.net>
            n0g0013 <ttw at cobbled.net> writes:
: trying to write a PCI driver and finding it awkward to build it
: outside the source tree.
: 
: will i have to wire in the new driver "sys" source tree to get a
: clean edit/build environment?
: 
: currently i'm doing two things
: 
: 	1.      merging my current kernel build directory with my
: 	new driver directory and building there.  it produces a
: 	module but leaves a hell of a mess.  the module reboots the
: 	system currently (no crash -- just reboot) but that may be
: 	something else.
: 
: 	2.      getting a copy of CVS so i can wire into tree when i
: 	understand how
: 
: if anyone could guide me on
: 
: 	a.      cleaner config for building modules in random
: 	directory (thought '-I' to make would work but it doesn't)
: 
: 	b.      how to actually wire in a new driver to the "sys"
: 	source tree (once i have a copy)
: 
: i'd appreciate it.

When I'm developing a new module, I do the following:

setenv SYSDIR /path/to/freebsd/src/sys
make

The Makefile looks like

# Maybe have a .PATH here

KMOD=	     foo
SRCS=	     foo_a foo_b

.include <bsd.kmod.mk>

At work, we wrap setting SYSDIR in an include file, since our build
system knows about it.

As for building a kernel with the driver in it, I'll leave that to
others.  We haven't built modules into the kernel on FreeBSD since
2.2.8.

Warner