Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753212AbaLYSCG (ORCPT ); Thu, 25 Dec 2014 13:02:06 -0500 Received: from mail-pa0-f44.google.com ([209.85.220.44]:38942 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752593AbaLYR5Z (ORCPT ); Thu, 25 Dec 2014 12:57:25 -0500 From: Kevin Cernekee To: ralf@linux-mips.org Cc: f.fainelli@gmail.com, jaedon.shin@gmail.com, abrestic@chromium.org, tglx@linutronix.de, jason@lakedaemon.net, jogo@openwrt.org, arnd@arndb.de, computersforpeace@gmail.com, linux-mips@linux-mips.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH V6 16/25] MIPS: BMIPS: Document the firmware->kernel DTB interface Date: Thu, 25 Dec 2014 09:49:11 -0800 Message-Id: <1419529760-9520-17-git-send-email-cernekee@gmail.com> X-Mailer: git-send-email 2.1.1 In-Reply-To: <1419529760-9520-1-git-send-email-cernekee@gmail.com> References: <1419529760-9520-1-git-send-email-cernekee@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a new section covering the Generic BMIPS machine type. Signed-off-by: Kevin Cernekee --- Documentation/devicetree/booting-without-of.txt | 28 +++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/Documentation/devicetree/booting-without-of.txt b/Documentation/devicetree/booting-without-of.txt index 7768518..e49e423 100644 --- a/Documentation/devicetree/booting-without-of.txt +++ b/Documentation/devicetree/booting-without-of.txt @@ -15,6 +15,7 @@ Table of Contents 1) Entry point for arch/arm 2) Entry point for arch/powerpc 3) Entry point for arch/x86 + 4) Entry point for arch/mips/bmips II - The DT block format 1) Header @@ -288,6 +289,33 @@ it with special cases. or initrd address. It simply holds information which can not be retrieved otherwise like interrupt routing or a list of devices behind an I2C bus. +4) Entry point for arch/mips/bmips +---------------------------------- + + Some bootloaders only support a single entry point, at the start of the + kernel image. Other bootloaders will jump to the ELF start address. + Both schemes are supported; CONFIG_BOOT_RAW=y and CONFIG_NO_EXCEPT_FILL=y, + so the first instruction immediately jumps to kernel_entry(). + + Similar to the arch/arm case (b), a DT-aware bootloader is expected to + set up the following registers: + + a0 : 0 + + a1 : 0xffffffff + + a2 : Physical pointer to the device tree block (defined in chapter + II) in RAM. The device tree can be located anywhere in the first + 512MB of the physical address space (0x00000000 - 0x1fffffff), + aligned on a 64 bit boundary. + + Legacy bootloaders do not use this convention, and they do not pass in a + DT block. In this case, Linux will look for a builtin DTB, selected via + CONFIG_DT_*. + + This convention is defined for 32-bit systems only, as there are not + currently any 64-bit BMIPS implementations. + II - The DT block format ======================== -- 2.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/