From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Sat, 10 Jan 2015 12:28:31 +0100 Subject: [Buildroot] [PATCH 5/5 v2] configs: add a DT-enabled Raspberry Pi defconfig In-Reply-To: <20150110121751.0bddd30b@free-electrons.com> References: <20150110121751.0bddd30b@free-electrons.com> Message-ID: <20150110122831.42767a7f@free-electrons.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hello, On Sat, 10 Jan 2015 12:17:51 +0100, Thomas Petazzoni wrote: > > - we can not use the minimalist RPi defconfig bundled with the kernel, > > namely bcmrpi_quick_defconfig, because it is not DT-enabled, and > > sets CONFIG_ARM_PATCH_PHYS_VIRT to 'n', which prompts a value for > > CONFIG_PHYS_OFFSET, as it as no default for the bcm familly; > > > > - we have to use the 'default' but bloated bcmrpi_defconfig, which > > makes for a very fat kernel with lots of modules, and takes ages to > > build; > > > > - most importantly, the rpi-3.18.y branch is constantly rebased, so > > there is no guarantee that the sha1 I use today will still be usable > > in the long term. Using the name of hte branch is not better either. > > Well, you could alternatively decide to have a custom kernel defconfig > in board/raspberrypi/, which would be the same as bcmrpi_quick, with > just the modifications you need for DT. Sure it means it will have to > be updated from time to time, but hopefully at some point in the future > the official bcmrpi_quick defconfig will have DT support enabled. Another motivation would be to switch back to an internal toolchain. Using an external toolchain here is quite inefficient: for an ARMv6 such as the RPi, we will fallback to the CodeSourcery toolchain, which will generate ARMv5 soft-float code. Not nice for a VFP-using ARMv6. Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com