path: root/Documentation/arm/Booting
diff options
Diffstat (limited to 'Documentation/arm/Booting')
1 files changed, 4 insertions, 29 deletions
diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting
index 4e686a2ed91e..76850295af8f 100644
--- a/Documentation/arm/Booting
+++ b/Documentation/arm/Booting
@@ -65,19 +65,13 @@ 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).
-4. Setup boot data
+4. Setup the kernel tagged list
New boot loaders: MANDATORY
-The boot loader must provide either a tagged list or a dtb image for
-passing configuration data to the kernel. The physical address of the
-boot data is passed to the kernel in register r2.
-4a. Setup the kernel tagged list
The boot loader must create and initialise the kernel tagged list.
A valid tagged list starts with ATAG_CORE and ends with ATAG_NONE.
The ATAG_CORE tag may or may not be empty. An empty ATAG_CORE tag
@@ -107,24 +101,6 @@ The tagged list must be placed in a region of memory where neither
the kernel decompressor nor initrd 'bootp' program will overwrite
it. The recommended placement is in the first 16KiB of RAM.
-4b. Setup the device tree
-The boot loader must load a device tree image (dtb) into system ram
-at a 64bit aligned address and initialize it with the boot data. The
-dtb format is documented in Documentation/devicetree/booting-without-of.txt.
-The kernel will look for the dtb magic value of 0xd00dfeed at the dtb
-physical address to determine if a dtb has been passed instead of a
-tagged list.
-The boot loader must pass at a minimum the size and location of the
-system memory, and the root filesystem location. The dtb must be
-placed in a region of memory where the kernel decompressor will not
-overwrite it. The recommended placement is in the first 16KiB of RAM
-with the caveat that it may not be located at physical address 0 since
-the kernel interprets a value of 0 in r2 to mean neither a tagged list
-nor a dtb were passed.
5. Calling the kernel image
@@ -149,8 +125,7 @@ In either case, the following conditions must be met:
- CPU register settings
r0 = 0,
r1 = machine type number discovered in (3) above.
- r2 = physical address of tagged list in system RAM, or
- physical address of device tree block (dtb) in system RAM
+ r2 = physical address of tagged list in system RAM.
- CPU mode
All forms of interrupts must be disabled (IRQs and FIQs)