From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Nelson Subject: Re: KConfig and DTS files Date: Thu, 08 May 2014 08:06:46 -0700 Message-ID: <536B9D86.3020806@boundarydevices.com> References: <536A697D.3020002@boundarydevices.com> <142702592.Qpp2HrZZke@wuerfel> <536A8456.1040208@boundarydevices.com> <5898724.4EExDycMZy@wuerfel> <536A8F03.5070509@boundarydevices.com> <536ABC89.8060301@boundarydevices.com> <20140508115532.GJ28159@titan.lakedaemon.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140508115532.GJ28159-u4khhh1J0LxI1Ri9qeTfzeTW4wlIGRCZ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Cooper Cc: Bjorn Andersson , Arnd Bergmann , Olof Johansson , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: devicetree@vger.kernel.org Hi Jason, On 05/08/2014 04:55 AM, Jason Cooper wrote: > On Wed, May 07, 2014 at 04:06:49PM -0700, Eric Nelson wrote: >> Hi Bjorn, >> >> On 05/07/2014 03:20 PM, Bjorn Andersson wrote: >>> On Wed, May 7, 2014 at 12:52 PM, Eric Nelson >>> wrote: >>> [...] >>>> >>>> I still wonder about the choice of not allowing inclusion >>>> of at least include/generated/autoconf.h. >>> >>> Because what you just showed is the use case where you have 1 defconfig, build 1 >>> zImage and then you can have a completely separate delivery of X number of >>> dtbs, all defining some variant of your original board. >>> All without recompiling, or even have the source available. >>> >> >> I agree that there's some benefit in being able to generate >> different DTBs, and it's an advantage (size, speed) to customize >> the .config as well. >> >> When those clearly go together, it seems natural to define them as >> such. > > But they don't. The end goal is that the dtb and the Linux kernel > _aren't_ tied together. The dtb is shipped with the board, and you > configure/build your kernel how you want, and boot it. > > Look at the dtb as replacement for the mach-type or boardid number. > It's handed to the OS (not necessarily Linux) by the bootloader to say > "Here's what you're running on". It's *not* a reflection of the > configuration of the Linux Kernel. The dtb describes the hardware for a > specific board. Nothing more, nothing less. > Therein lies the rub... In these days of SOCs with pin-muxing, a single description of "the board" is overly simplistic. > Several other projects use the dts files from the kernel tree. Ian > Campbell even set up a filter-branch version of the dts files and the > binding docs so that other projects could clone that repo without > getting the entire Linux commit history. If we tied the dts files to > Kconfig symbols, we'd make other projects lives much more difficult. > Not to mention possibly driving Ian to drink excessively. :) > Again, this highlights differing goals. My original question stemmed from a **desire** for customized DTBs to reflect customization of a board. We have dozens of custom and semi-custom versions of our tying these parts together would make things a bit easier. Regards, Eric -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html