On Tue, Nov 25, 2014 at 11:51:50PM +0000, Russell King - ARM Linux wrote: > 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. Linus, since you were the one experiencing the regression, care to take a whack at that? thx, Jason. -- 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
