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Documentation: arm: Update for DT-only platforms

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 <gregory.0xf0@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

authored by

Gregory Fong and committed by
Jonathan Corbet dce12391 c517d838

+18 -6
+7 -2
Documentation/arm/Booting
··· 58 58 -------------------------- 59 59 60 60 Existing boot loaders: OPTIONAL 61 - New boot loaders: MANDATORY 61 + New boot loaders: MANDATORY except for DT-only platforms 62 62 63 63 The boot loader should detect the machine type its running on by some 64 64 method. Whether this is a hard coded value or some algorithm that 65 65 looks at the connected hardware is beyond the scope of this document. 66 66 The boot loader must ultimately be able to provide a MACH_TYPE_xxx 67 - value to the kernel. (see linux/arch/arm/tools/mach-types). 67 + value to the kernel. (see linux/arch/arm/tools/mach-types). This 68 + should be passed to the kernel in register r1. 69 + 70 + For DT-only platforms, the machine type will be determined by device 71 + tree. set the machine type to all ones (~0). This is not strictly 72 + necessary, but assures that it will not match any existing types. 68 73 69 74 4. Setup boot data 70 75 ------------------
+11 -4
Documentation/arm/README
··· 185 185 board devices are used, or the device is setup, and provides that 186 186 machine specific "personality." 187 187 188 - This fine-grained machine specific selection is controlled by the machine 189 - type ID, which acts both as a run-time and a compile-time code selection 190 - method. 188 + For platforms that support device tree (DT), the machine selection is 189 + controlled at runtime by passing the device tree blob to the kernel. At 190 + compile-time, support for the machine type must be selected. This allows for 191 + a single multiplatform kernel build to be used for several machine types. 191 192 192 - You can register a new machine via the web site at: 193 + For platforms that do not use device tree, this machine selection is 194 + controlled by the machine type ID, which acts both as a run-time and a 195 + compile-time code selection method. You can register a new machine via the 196 + web site at: 193 197 194 198 <http://www.arm.linux.org.uk/developer/machines/> 199 + 200 + Note: Please do not register a machine type for DT-only platforms. If your 201 + platform is DT-only, you do not need a registered machine type. 195 202 196 203 --- 197 204 Russell King (15/03/2004)