From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Mon, 01 Sep 2014 10:24:17 +0200 Subject: [PATCH 1/2] ARM: multi_v7_defconfig: Enable shmobile platforms In-Reply-To: References: <1409234429-1916-1-git-send-email-geert+renesas@glider.be> <3598124.ze8sbSR9ui@wuerfel> Message-ID: <3848521.UcIm3L3emN@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Saturday 30 August 2014 11:32:30 Geert Uytterhoeven wrote: > Hi Arnd, > > On Fri, Aug 29, 2014 at 10:11 PM, Arnd Bergmann wrote: > > A related problem that I think is more significant is that > > some platforms 'select' a particular driver and when you > > disable the platform, that driver is suddenly removed from the > > defconfig for all other platforms as well. This has bitten > > us a few times in the past, and I'd really like to fix those > > cases first. > > Indeed. "select" is evil, and has a devastating effect on minimal > defconfigs (lots of churn and nasty surprises like the one you mentioned). > > So it actually makes more sense to derive multi_v7_defconfig > from the individual platform's defconfigs. > I also have a script for that, which I wrote to create m68k's multi_defconfig > a long time ago: > https://github.com/geertu/linux-scripts/blob/master/linux-config-merge This looks like a very interesting method, and is similar to the "Kconfig fragments" that a lot of people are using. However I'm not sure we can replace the multi_v7_defconfig with it, the main problem I see with that is that it can get unpredictable when changes are done to one of the inputs. I'd rather keep the multi_v7_defconfig in some form (possibly extend it to v6) and use fragments for some specialized variation (v6-smp, v7, v7-lpae, ...). > In the long run, I think creating defconfigs from DTS is the way to go. > Extracting dependencies from the build system (both Makefile and > the myriad of complex dependencies in Kconfig) are the biggest hurdles to > solve. Yes, this looks like very interesting work. We won't be able to use it for all cases, in particular for distro kernels that are meant to run on a large number of machines that don't all have dts files in the kernel, but it should simplify the workflow for a lot of embedded use cases. Arnd