On Tue, Nov 25, 2014 at 10:41:35PM +0100, Michal Marek wrote: > Dne 2.11.2014 v 21:52 Jason Cooper napsal(a): > > After this patch: > > > > f4d4ffc03efc kbuild: dtbs_install: new make target > > > > was added the kernel tree, Linus Walleij noticed that 'make dtbs' forced > > a following 'make zImage' to rebuild the entire tree, even though > > nothing had changed. His report: > > > > After this patch a while back I have observed the following behaviour > > of the kernel build: > > > > make zImage > > make zImage > > -> incremental build, just relink > > > > make zImage > > make dtbs > > make zImage > > -> The whole kernel gets rebuilt > > > > So now if I happen to recompile my device trees, I suddenly want > > the entire zImage to be rebuilt to? It's by definition not changes > > that affect the kernel build :-( > > > > I noticed this because my build scripts calls make dtbs && make > > zImage, and started to rebuild absolutely everything all the time. > > > > To fix this, we make only the dtbs_install target depend on the prepare > > target. It's needed to make sure KERNELVERSION is calculated prior to > > installing. > > If a mere 'make prepare' causes a rebuild of the whole kernel, then > there is something fishy in the ARM Makefiles. However, if you only need > the KERNELRELEASE variable, then you do not need to depend on prepare. > The main Makefile makes sure that silentoldconfig is ran and therefore > KERNELRELEASE set for all targets except make *config. Running make prepare and then re-running a build doesn't rebuild anything for me. However, I always build with O= Also works if I do a make dtbs too. So, everything seems to work as expected here. I think this needs a bit more debugging to see why the whole kernel is being rebuilt - the kernel build system has methods to tell you why stuff is being built, which would be a good place to start. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
