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[216.31.211.11]) by mx.google.com with ESMTPSA id bi11sm290658pdb.8.2015.02.03.18.49.48 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 03 Feb 2015 18:49:48 -0800 (PST) From: Gregory Fong To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] Documentation: arm: Update for DT-only platforms Date: Tue, 3 Feb 2015 18:49:26 -0800 Message-Id: <1423018169-31221-1-git-send-email-gregory.0xf0@gmail.com> X-Mailer: git-send-email 1.9.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150203_185011_532943_0D961B22 X-CRM114-Status: GOOD ( 14.55 ) X-Spam-Score: -0.6 (/) Cc: Russell King , "open list:DOCUMENTATION" , linux-kernel@vger.kernel.org, Gregory Fong , Jonathan Corbet X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.1 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_MED, T_DKIM_INVALID, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The documentation specified that a machine type is mandatory and made that assumption in a few places. However, for DT-only platforms, the current advice is that no machine type should be registered, so update accordingly. Signed-off-by: Gregory Fong --- Documentation/arm/Booting | 9 +++++++-- Documentation/arm/README | 15 +++++++++++---- 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting index 371814a..83c1df2 100644 --- a/Documentation/arm/Booting +++ b/Documentation/arm/Booting @@ -58,13 +58,18 @@ serial format options as described in -------------------------- Existing boot loaders: OPTIONAL -New boot loaders: MANDATORY +New boot loaders: MANDATORY except for DT-only platforms The boot loader should detect the machine type its running on by some method. Whether this is a hard coded value or some algorithm that looks at the connected hardware is beyond the scope of this document. The boot loader must ultimately be able to provide a MACH_TYPE_xxx -value to the kernel. (see linux/arch/arm/tools/mach-types). +value to the kernel. (see linux/arch/arm/tools/mach-types). This +should be passed to the kernel in register r1. + +For DT-only platforms, the machine type will be determined by device +tree. set the machine type to all ones (~0). This is not strictly +necessary, but assures that it will not match any existing types. 4. Setup boot data ------------------ diff --git a/Documentation/arm/README b/Documentation/arm/README index aea3409..9d1e5b2 100644 --- a/Documentation/arm/README +++ b/Documentation/arm/README @@ -185,13 +185,20 @@ Kernel entry (head.S) board devices are used, or the device is setup, and provides that machine specific "personality." - This fine-grained machine specific selection is controlled by the machine - type ID, which acts both as a run-time and a compile-time code selection - method. + For platforms that support device tree (DT), the machine selection is + controlled at runtime by passing the device tree blob to the kernel. At + compile-time, support for the machine type must be selected. This allows for + a single multiplatform kernel build to be used for several machine types. - You can register a new machine via the web site at: + For platforms that do not use device tree, this machine selection is + controlled by the machine type ID, which acts both as a run-time and a + compile-time code selection method. You can register a new machine via the + web site at: + Note: Please do not register a machine type for DT-only platforms. If your + platform is DT-only, you do not need a registered machine type. + --- Russell King (15/03/2004)