From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Grandegger Date: Tue, 29 Jul 2008 10:41:32 +0200 Subject: [U-Boot-Users] using a flat device tree to drive u-boot config In-Reply-To: <488ED426.2070502@matrix-vision.de> References: <488E02C7.5000106@freescale.com> <488E053A.40205@freescale.com> <488ED426.2070502@matrix-vision.de> Message-ID: <488ED7BC.1050905@grandegger.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Andr? Schwarz wrote: > Ben Warren schrieb: >> On Mon, Jul 28, 2008 at 10:43 AM, Scott Wood wrote: >>> Ben Warren wrote: >>>> On Mon, Jul 28, 2008 at 10:32 AM, Scott Wood >>>> wrote: >>>>> I find a device tree much easier to figure out than a tangled mess of >>>>> header >>>>> files, #defines, and #ifdefs... >>>> In many ways, yes. But are you an average Joe or a Linux kernel >>>> propellerhead? >>> Is u-boot work normally done by average Joes, and does the average Joe >>> really find the preprocessor mess more intuitive than a "propellerhead"? >>> >> You know what I mean. Some people like yourself do this for a living, >> and are involved day-to-day in its specification. Of course it's >> intuitive to you. For most people, getting U-boot going is one stage >> in the development process of software for an embedded device. They >> work on it for a few weeks or months, then on something completely >> different. A few months or years later, they come back to it. > > You're absolutely right - just have a look at the vast lists of > maintainers/contributors ... they are "average Joes" like myself. > Realizing 2-3 projects each year should be possible without having to > re-learn from scratch. > >>> While we're at it, let's re-write u-boot in Visual Basic. :-) >> Uh, yeah. I like the idea of a central repo for hardware info, and >> the device tree concept is good. My point is that the syntax, while >> concise and exact, can be intimidating. Just look at the amount of >> traffic on the mailing lists of people that don't understand what all >> the fields mean when specifying IRQs etc. Anything we can do to make >> it less so for noobies is a good thing for everybody. >> > > Please keep in mind that WDenk is always watching if code is slowing > things down or increasing size significantly. Improving things is very > good - but not at the cost of size and/or speed. Configuring a board > using a dtb usually needs far more code being present than needed. > After all it's a bootloader and not another pseudo OS. > > But don't get me wrong ! The device tree is a very nice and usefuly > thing ... for an OS. There are customer request for a dynamically configurable U-Boot and the FDT is the right tool to provide the functionality. It has its price but U-Boot using a FDT blob for booting would also save some fixup code (required to boot Linux) and furthermore it would resolves some dependencies between hardcoded U-Boot and FDT defined addresses and ranges. Wolfgang.