Date: Fri, 21 Sep 2007 12:08:21 +0200 From: Rafal Jaworowski <raj@semihalf.com> To: "Stephane E. Potvin" <sepotvin@videotron.ca> Cc: grehan@freebsd.org, freebsd-ppc@freebsd.org Subject: Re: Cell port Message-ID: <46F39815.6060507@semihalf.com> In-Reply-To: <46F28001.2030205@videotron.ca> References: <E79BC169-E7E8-4CA2-95E8-FC806777714E@decpp.net> <46DCD1DA.5090301@freebsd.org> <42C14314-D3EC-460E-97D9-53830FB9CBF6@decpp.net> <46E03D3E.8060504@freebsd.org> <46F28001.2030205@videotron.ca>
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Stephane E. Potvin wrote: > > Small comment about the OpenFirmware dependency. Recent Linux kernels > started to required that all powerpc platforms provide what they call a > "flattened device tree" which is very similar to an OpenFirmware device > tree. It enables them to share the same code for standard Apple > computers providing an OpenFirmware and small embedded processors (like > the 8349e from FSL) that do not usually have OpenFirmware. > > It might be worthwhile for anybody attempting to port to a new > architecture to look into adding support for something similar instead > of removing the OF dependency. > Having the flat device tree is not cheap, as one has to provide the whole infrastructure, which is currently non-existent: - the dtc 'compiler' to produce binary out of textual description of the device tree (the existing GPL-licensed could be used for quick start) - in-kernel library of routines processing the device tree blob (node, properties etc.) - loader(8) would need to be involved too (at least to pass the blob as part of metadata or so). Introducing this is quite a big project for its own, and requires dealing with OpenFirmware internals, binding definitions etc. as FDT essentially mimics some part of it. Rafal
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