From mboxrd@z Thu Jan 1 00:00:00 1970 From: Federico Vaga Subject: Re: DeviceTree FPGA bitstream Date: Mon, 15 Jun 2015 10:55:46 +0200 Message-ID: <20150615085546.GA19162@pcbe13110.cern.ch> References: <20150609144901.GC12677@pcbe13110.cern.ch> <55796021.7010402@home.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: <55796021.7010402-CmkmPbn3yAE@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Walter Goossens Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Walter, On Thu, Jun 11, 2015 at 12:17:05PM +0200, Walter Goossens wrote: > On 06/09/2015 04:49 PM, Federico Vaga wrote: >> - it looks like the DeviceTree is disable for x86 architecture except for >> some specific platform. Is it possible to enable it for the entire x86 >> architecture? Are there any reason to disable it by default? >> >> - I read that since versione 3.17 it should be possible to dynamically >> add >> portion of DeviceTree from configfs. Is it possible on all architecture? >> >> - I'm working on x86_64 and my FPGA can be on a pluggable board (e.g. >> PCIe). >> Is there a way to describe this situation with DeviceTree? Is there >> any tool >> that dynamically computes the addresses (interrupts) translation to use >> (e.g. on PCIe) ? >> > > I've been using this scheme on PPC for quite some time (before > devicetree overlays) by creating a custom pcie driver (that knows the > bar addresses and irqs) which then instantiates a "virtual platformbus" > at the pcie bar the fpga is located in. > You can adopt this scheme for x86 by creating a bus and using the > devicetree code to probe the inside of your FPGA but this is all a bit > hackish. > The correct approach (in my opinion) would be to use an overlay > describing the contents of the FPGA and loading that when probing the > pcie-device. This is more or less what I thought > This would however require a base devicetree to apply the > overlay to, and I'm not sure how much effort this is going to be on x86_64 Not sure but I fear that is not enough to make it stable. The compilation of the DeviceTree is allowed only on x86 and on some specific platform. Of course, I can modify the Kconfig to allow the compilation of the DeviceTree but then I don't know if it will work and how it will work. I mean are there particular reasons to keep the DeviceTree away from x86 ? -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html