diff options
Diffstat (limited to 'Documentation/arm/Booting')
| -rw-r--r-- | Documentation/arm/Booting | 33 |
1 files changed, 4 insertions, 29 deletions
diff --git a/Documentation/arm/Booting b/Documentation/arm/Booting index 4e686a2ed91..76850295af8 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 +------------------------------- Existing boot loaders: OPTIONAL, HIGHLY RECOMMENDED 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) |