RE: Default NO_CLEAN=yes in 15+

John Baldwin <jhb_at_FreeBSD.org> wrote on
Date: Tue, 23 Jul 2024 19:58:13 UTC :

> The buildworld and buildkernel targets include a "clean" step before building
> objects dating back before my time to 'make world' (I haven't looked to see
> how far back it goes). To permit incremental builds, this step can be skipped
> via NO_CLEAN=yes. This step is a bit unusual in build systems however. Most
> build systems have separate commands for building vs cleaning (e.g. 'make all'
> vs 'make clean') and over time FreeBSD's build system has gained dedicated
> clean targets as well (cleanworld and cleankernel). For myself, I always
> use NO_CLEAN=yes when building worlds and kernels. If I need a clean build
> I use the dedicated clean targets (e.g. cleanworld) first. In particular,
> cleanworld/cleankernel are far more efficient since they use a single
> recursive 'rm' whereas the "clean" step involves a full tree walk with
> nested make invocations of the 'cleandir' target.
> 
> A few years ago, Ed Maste added a MK_CLEAN option to src.opts.mk to as a
> WITH/WITHOUT knob for the "clean" step similar to NO_CLEAN=yes. To preserve
> existing behavior this knob currently defaults to on, but I know Ed's goal
> was to eventually flip the default so that NO_CLEAN builds would be the
> default. I would like us to do that starting in 15.
> 
> Further off, I would suggest that we remove the "clean" step outright,
> perhaps in 16.x. Regardless, we will need to update documentation to
> prefer the clean targets over WITH_CLEAN=yes if our docs do not do this
> already.

I use META_MODE and do not explicitly control NO_CLEAN. Any implications
for META_MODE for this change?

===
Mark Millard
marklmi at yahoo.com