From owner-freebsd-hackers@FreeBSD.ORG Mon Nov 26 15:06:23 2012 Return-Path: Delivered-To: hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 2726A786 for ; Mon, 26 Nov 2012 15:06:23 +0000 (UTC) (envelope-from kientzle@freebsd.org) Received: from monday.kientzle.com (99-115-135-74.uvs.sntcca.sbcglobal.net [99.115.135.74]) by mx1.freebsd.org (Postfix) with ESMTP id EA1A38FC14 for ; Mon, 26 Nov 2012 15:06:22 +0000 (UTC) Received: (from root@localhost) by monday.kientzle.com (8.14.4/8.14.4) id qAQF5drf038915; Mon, 26 Nov 2012 15:05:39 GMT (envelope-from kientzle@freebsd.org) Received: from [192.168.2.143] (CiscoE3000 [192.168.1.65]) by kientzle.com with SMTP id m25h4wdmkh8yx6h4ywna4qp6de; Mon, 26 Nov 2012 15:05:39 +0000 (UTC) (envelope-from kientzle@freebsd.org) Subject: Re: FreeBSD on RaspberryPi Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: text/plain; charset=us-ascii From: Tim Kientzle In-Reply-To: Date: Mon, 26 Nov 2012 07:05:37 -0800 Content-Transfer-Encoding: quoted-printable Message-Id: <1E75CEAC-32E8-4048-A1FB-DD59F996E22F@freebsd.org> References: <31C904E6-F230-4187-AE32-F9A7B1A7C38E@freebsd.org> <4A5E03E5-3295-4FD4-9A06-7D1C4E9E0C12@freebsd.org> <9E4DA920-BE72-4AA0-8159-43205CDEF5CD@bluezbox.com> To: Oleksandr Tymoshenko X-Mailer: Apple Mail (2.1283) Cc: FreeBSD Hackers , Alexander Yerenkow X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Nov 2012 15:06:23 -0000 On Nov 25, 2012, at 11:46 PM, Oleksandr Tymoshenko wrote: >=20 > On 2012-11-25, at 9:32 AM, Tim Kientzle wrote: >=20 >>=20 >> On Nov 24, 2012, at 8:01 PM, Oleksandr Tymoshenko wrote: >>=20 >>>=20 >>> On 2012-11-24, at 4:47 PM, Tim Kientzle = wrote: >>>=20 >>>=20 >=20 > .. skipped .. >=20 >>> Tim, >>>=20 >>> I'm almost done with getting kernel working with latest raspberry Pi = firmware. Just need >>> to figure out how to make ubldr pass FDT pointer from u-boot to = kernel and handle=20 >>> /reserve/ information in ARM machdep code.=20 >>=20 >> Let me know if you need help with this. I've worked with >> the ubldr FDT code recently. >>=20 >>> Meanwhile I suggest editing .dts file manually. Fill out "display" = node properties with proper >>> display resolution and depth. Also add ukbd driver. That should get = you working console. >>=20 >> I'll try that. >>=20 >> I'm curious: why is this information coming from the DTS? >> That seems pretty complex; I thought that the >> console code would query this information via the mailbox >> interface. >=20 >=20 > It's either FDT blob or message box interface. Implementation = complexity is about the same. My thinking: * Display resolution used by kernel has to match what the firmware = uses. So the kernel should either get the information from the firmware = or from the same place the firmware gets it from. * We want ubldr to remain generic, so I'm reluctant to put things into = it that are RaspberryPi-specific. If the firmware is putting the values into the FDT, then having the = kernel get it from the FDT is another way for the kernel to get it from = the firmware, so that sounds okay. > But since we're getting other variables (like MAC address, memory = size) from FDT I decided > to be consistent and get all of them from there. I don't know about MAC address. Memory size is handled generically by = ubldr using a standard interface to U-Boot, so it's not special to = RaspberryPi. The FDT editing is just a standard way for ubldr to pass = this to the kernel. > The issue I'm facing is that ubldr gets FDT blob > either from file directly or from ELF kernel itself. While on = Raspberry Pi to works as follows: >=20 > - Firmware loads .dtb file from SD card to specified address Does RaspberryPi firmware now load an FDT? Does the firmware now read the FDT to get its values for display = resolution, etc? (I don't really like this because a lot of people need to tweak the = display settings and it's hard to tell a 6-year-old how to edit and = recompile an FDT.) > - Fixes up values like amount of memory, reserved regions, UART and = clock frequencies,=20 > MAC address, display resolution. > - Passes control to next link in boot chain (e.g. U-Boot) To be clear: You say the RPi firmware is already doing this editing? So the ubldr just has to pass the RPi FDT to the kernel? If so, that's = a lot simpler. > I'm thinking about adding compile-time constant FDT_BLOB_ADDRESS and = arrange possible > FDT sources in following priority: >=20 > - Check FDT_BLOB_ADDRESS (if defined) > - Check dtb file > - Check ELF kernel >=20 > Does it sound sane enough?=20 If the RPi firmware always loads the FDT at a fixed address and the RPi firmware is using the FDT to configure itself, then it makes a lot of sense. It would be nice to do this without adding RPi-specific code to ubldr. > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to = "freebsd-hackers-unsubscribe@freebsd.org" >=20