diff options
| author |   Gregory Fong <gregory.0xf0@gmail.com> | 2015-02-03 18:49:26 -0800 |
|---|---|---|
| committer |   Jonathan Corbet <corbet@lwn.net> | 2015-02-27 14:54:55 -0700 |
| commit | dce12391d70d24d428def2f5fc600a3b1f791ca6 (patch) | |
| tree | b2bf6217ace4b44017982185d0d294e1b78616d8 /Documentation/arm | |
| parent | Linux 4.0-rc1 (diff) | |
| download | linux-dev-dce12391d70d24d428def2f5fc600a3b1f791ca6.tar.xz linux-dev-dce12391d70d24d428def2f5fc600a3b1f791ca6.zip | |
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>
Diffstat (limited to 'Documentation/arm')
| -rw-r--r-- | Documentation/arm/Booting | 9 | ||||
| -rw-r--r-- | Documentation/arm/README | 15 |
2 files changed, 18 insertions, 6 deletions
diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting index 371814a36719..83c1df2fc758 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 aea34095cdcf..9d1e5b2c92e6 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: <http://www.arm.linux.org.uk/developer/machines/> + 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) |