Date: Tue, 23 Jul 2024 17:29:12 -0400 From: John Baldwin <jhb@FreeBSD.org> To: Shawn Webb <shawn.webb@hardenedbsd.org> Cc: arch@freebsd.org Subject: Re: Default NO_CLEAN=yes in 15+ Message-ID: <71d28fd9-7679-4aaa-981e-81fa70c5da71@FreeBSD.org> In-Reply-To: <ia2xwmohoomnica7vp7hotd7sknovyyb3hgkfrx6blekbx6qdn@aax3blyqxcer> References: <9bbb12ee-d5e0-4e9c-a832-bbfe5eea0ba6@FreeBSD.org> <ia2xwmohoomnica7vp7hotd7sknovyyb3hgkfrx6blekbx6qdn@aax3blyqxcer>
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On 7/23/24 16:08, Shawn Webb wrote: > On Tue, Jul 23, 2024 at 03:58:13PM -0400, John Baldwin wrote: >> 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. > > It would make sense to me to default MK_CLEAN=no in release branches. > Perhaps stable branches, too. While I don't hold a strong opinion on > the matter, I would prefer MK_CLEAN=yes to remain the default on the > main branch. > > I can't give tangible examples, but I remember running into weird > issues occasionally when using `make buildworld WITHOUT_CLEAN=yes` in > main. I probably should do a better job at documenting those > (infrequent) issues when they arise. To be clear, the suggestion is that when you hit an issue, just run 'make cleanworld' rather than relying on the omission of NO_CLEAN=yes to do this for you (and much slower at that). Have you used any other build systems where 'make' does an implicit 'make clean' before it builds? I have never encountered another where this is true. 'clean' is always a separate target from 'all' in my experience. -- John Baldwin
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