From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail21-dub-R.bigfish.com (mail-dub.bigfish.com [213.199.154.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "*.bigfish.com", Issuer "*.bigfish.com" (not verified)) by ozlabs.org (Postfix) with ESMTP id 549EFDDE18 for ; Thu, 18 Oct 2007 02:22:33 +1000 (EST) MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Subject: RE: Merge dtc Date: Wed, 17 Oct 2007 09:22:00 -0700 In-Reply-To: References: <20071016050217.GA9052@localhost.localdomain><20071017052220.GA3801@localhost.localdomain> From: "Stephen Neuendorffer" To: "Grant Likely" , "Paul Mackerras" , "Josh Boyer" , Message-Id: <20071017162227.8E7F3470071@mail21-dub.bigfish.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , =20 > -----Original Message----- > From:=20 > linuxppc-dev-bounces+stephen.neuendorffer=3Dxilinx.com@ozlabs.or > g=20 > [mailto:linuxppc-dev-bounces+stephen.neuendorffer=3Dxilinx.com@o zlabs.org] On Behalf Of Grant Likely > Sent: Wednesday, October 17, 2007 6:15 AM > To: Grant Likely; Paul Mackerras; Josh Boyer; linuxppc-dev@ozlabs.org > Subject: Re: Merge dtc >=20 > On 10/16/07, David Gibson wrote: > > On Tue, Oct 16, 2007 at 07:17:01AM -0600, Grant Likely wrote: > > > On 10/15/07, David Gibson wrote: > > > > This very large patch incorporates a copy of dtc into the kernel > > > > source, in arch/powerpc/boot/dtc-src. This means that dtc is no > > > > longer an external dependency to build kernels with=20 > configurations > > > > which need a dtb file. > > > > > > Powerpc is probably not going to be the only user of dtc.=20 > Microblaze > > > will be using it too. Can it be put somewhere more common? > > > > Well, I guess we can move it to scripts/ when microblaze=20 > starts using > > it. > > > > Also, tell me more about this microblaze, I'm certainly=20 > interested in > > new users of dtc... >=20 > It's a 'soft processor'. Implemented in the fabric of an FPGA. It's > a ucLinux target. Xilinx Virtex and Xilinx MicroBlaze targets share a > lot of common devices. >=20 > Cheers, > g. Basically, this partially works today. Most of the device information can come out of a flat device tree, with most of the kernel code copied straight from arch/powerpc. I'm still trying to sort out how some of the architecture specific stuff can be extracted in a smart way. For instance, the microblaze has configurable cache sizes, and may or may not be available. Currently, this is #defined in the kernel, but I'd like to get to the point where the same information is pulled out of a device tree. My main quandry at the moment is that I'm not wild about self-modifying code and I'm not sure if the extra overhead of implementing it with conditionals is significant. In any event, my plan is to get this into a reasonable state and then post it here for review. The main reason why we went with flat device trees for this was to get as much symmettry as possible between the soft microblaze and the embedded ppc405 hard core in some FPGAs. Steve