From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Date: Tue, 10 Jan 2017 18:34:35 +0000 Subject: [U-Boot] [RFC PATCH] arm: bootm: Boot kernel with U-Boot's FDT blob In-Reply-To: References: <2b4f0cab210294fccacd639c13cae038ca842f6b.1484053094.git.michal.simek@xilinx.com> <0da73708-605b-780f-a38d-6af34ece60fc@suse.de> <0c69ad6e-82ce-57a0-d392-e154115d0ca3@suse.de> Message-ID: <20170110183435.GA25493@leverpostej> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Tue, Jan 10, 2017 at 05:17:07PM +0000, Ryan Harkin wrote: > On 10 January 2017 at 16:58, Alexander Graf wrote: > > On 01/10/2017 05:47 PM, Ryan Harkin wrote: > >> I have a background task to refactor u-boot support for ARM Ltd > >> boards. One of many options I was considering was to have a minimal > >> DTB to configure the platform with only the nodes needed for u-boot. > >> The ARM Ltd device trees fluctuate so much, I wouldn't be able to > >> commit to one DTB that will work forever... > > > > No, it's only meant as a fallback when no manual device tree is provided. > > Thanks for confirmation. > > > In an ideal world however, device trees are static and complete, so > > you could just put a final dt into U-Boot and have it propagated all > > the way through. > > I look forward to living in this ideal world the EDK2 and kernel > communities promised me several years ago ;-) To be fair, the *upstream* DTs for ARM Ltd platforms are relatively stable. I must assume you're talking about random platform trees from elsewhere, which it's not fair to blame the EDK2 or Linux communities for. ;) Looking at the git log for arch/arm64/boot/dts/arm, most updates are simply adding new descriptions, so a DTB from a year ago should work just fine with mainline (modulo the Juno PCI window issue, which was a DTB bug). Upgrading kernel shouldn't require a DTB upgrade to see equivalent functionality. It's certainly not great that those aren't in a separate canonical repo, but in terms of stability we are largely there, random *not upstream* platform trees notwithstanding. We'll never get complete from day one, so some updates over time are a fact of life, but we are in the position to ship something that continues to work... Thanks, Mark.