Date: Fri, 21 Sep 2007 13:20:16 -0400 From: "Stephane E. Potvin" <sepotvin@videotron.ca> To: Rafal Jaworowski <raj@semihalf.com> Cc: grehan@freebsd.org, freebsd-ppc@freebsd.org Subject: Re: Cell port Message-ID: <46F3FD50.6030409@videotron.ca> In-Reply-To: <46F39815.6060507@semihalf.com> 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> <46F39815.6060507@semihalf.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Rafal Jaworowski wrote: > 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. > I admit that I might be confused but I thought that the ppc port already had the infrastructure to deal with OF. As the FDT is a simplified OF tree (flattened), once you have the blob parser it should be pretty straightforward. At least not much more complicated than to rip out the OF dependency and have to maintain two different ways of probing the HW. This being said, even if I have a very strong interest in this area I don't have enough resources at this time to work on this, so I'll leave those who work on this decide which way is better. Regards, Steph
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?46F3FD50.6030409>