Loading Documentation/arm/Booting +29 −4 Original line number Diff line number Diff line Loading @@ -65,13 +65,19 @@ 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 the kernel tagged list ------------------------------- 4. Setup boot data ------------------ 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 Loading Loading @@ -101,6 +107,24 @@ 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 --------------------------- Loading @@ -125,7 +149,8 @@ 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. r2 = physical address of tagged list in system RAM, or physical address of device tree block (dtb) in system RAM - CPU mode All forms of interrupts must be disabled (IRQs and FIQs) Loading Documentation/devicetree/booting-without-of.txt +44 −4 Original line number Diff line number Diff line Loading @@ -12,8 +12,9 @@ Table of Contents ================= I - Introduction 1) Entry point for arch/powerpc 2) Entry point for arch/x86 1) Entry point for arch/arm 2) Entry point for arch/powerpc 3) Entry point for arch/x86 II - The DT block format 1) Header Loading Loading @@ -148,7 +149,46 @@ upgrades without significantly impacting the kernel code or cluttering it with special cases. 1) Entry point for arch/powerpc 1) Entry point for arch/arm --------------------------- There is one single entry point to the kernel, at the start of the kernel image. That entry point supports two calling conventions. A summary of the interface is described here. A full description of the boot requirements is documented in Documentation/arm/Booting a) ATAGS interface. Minimal information is passed from firmware to the kernel with a tagged list of predefined parameters. r0 : 0 r1 : Machine type number r2 : Physical address of tagged list in system RAM b) Entry with a flattened device-tree block. Firmware loads the physical address of the flattened device tree block (dtb) into r2, r1 is not used, but it is considered good practise to use a valid machine number as described in Documentation/arm/Booting. r0 : 0 r1 : Valid machine type number. When using a device tree, a single machine type number will often be assigned to represent a class or family of SoCs. r2 : physical pointer to the device-tree block (defined in chapter II) in RAM. Device tree can be located anywhere in system RAM, but it should be aligned on a 64 bit boundary. The kernel will differentiate between ATAGS and device tree booting by reading the memory pointed to by r2 and looking for either the flattened device tree block magic value (0xd00dfeed) or the ATAG_CORE value at offset 0x4 from r2 (0x54410001). 2) Entry point for arch/powerpc ------------------------------- There is one single entry point to the kernel, at the start Loading Loading @@ -226,7 +266,7 @@ it with special cases. cannot support both configurations with Book E and configurations with classic Powerpc architectures. 2) Entry point for arch/x86 3) Entry point for arch/x86 ------------------------------- There is one single 32bit entry point to the kernel at code32_start, Loading arch/arm/Kconfig +7 −0 Original line number Diff line number Diff line Loading @@ -1683,6 +1683,13 @@ endmenu menu "Boot options" config USE_OF bool "Flattened Device Tree support" select OF select OF_EARLY_FLATTREE help Include support for flattened device tree machine descriptions. # Compressed boot loader in ROM. Yes, we really want to ask about # TEXT and BSS so we preserve their values in the config files. config ZBOOT_ROM_TEXT Loading arch/arm/include/asm/mach/arch.h +9 −0 Original line number Diff line number Diff line Loading @@ -18,6 +18,8 @@ struct machine_desc { unsigned int nr; /* architecture number */ const char *name; /* architecture name */ unsigned long boot_params; /* tagged list */ const char **dt_compat; /* array of device tree * 'compatible' strings */ unsigned int nr_irqs; /* number of IRQs */ Loading Loading @@ -47,6 +49,13 @@ struct machine_desc { */ extern struct machine_desc *machine_desc; /* * Machine type table - also only accessible during boot */ extern struct machine_desc __arch_info_begin[], __arch_info_end[]; #define for_each_machine_desc(p) \ for (p = __arch_info_begin; p < __arch_info_end; p++) /* * Set of macros to define architecture features. This is built into * a table by the linker. Loading arch/arm/include/asm/prom.h 0 → 100644 +37 −0 Original line number Diff line number Diff line /* * arch/arm/include/asm/prom.h * * Copyright (C) 2009 Canonical Ltd. <jeremy.kerr@canonical.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #ifndef __ASMARM_PROM_H #define __ASMARM_PROM_H #ifdef CONFIG_OF #include <asm/setup.h> #include <asm/irq.h> static inline void irq_dispose_mapping(unsigned int virq) { return; } extern struct machine_desc *setup_machine_fdt(unsigned int dt_phys); extern void arm_dt_memblock_reserve(void); #else /* CONFIG_OF */ static inline struct machine_desc *setup_machine_fdt(unsigned int dt_phys) { return NULL; } static inline void arm_dt_memblock_reserve(void) { } #endif /* CONFIG_OF */ #endif /* ASMARM_PROM_H */ Loading
Documentation/arm/Booting +29 −4 Original line number Diff line number Diff line Loading @@ -65,13 +65,19 @@ 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 the kernel tagged list ------------------------------- 4. Setup boot data ------------------ 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 Loading Loading @@ -101,6 +107,24 @@ 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 --------------------------- Loading @@ -125,7 +149,8 @@ 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. r2 = physical address of tagged list in system RAM, or physical address of device tree block (dtb) in system RAM - CPU mode All forms of interrupts must be disabled (IRQs and FIQs) Loading
Documentation/devicetree/booting-without-of.txt +44 −4 Original line number Diff line number Diff line Loading @@ -12,8 +12,9 @@ Table of Contents ================= I - Introduction 1) Entry point for arch/powerpc 2) Entry point for arch/x86 1) Entry point for arch/arm 2) Entry point for arch/powerpc 3) Entry point for arch/x86 II - The DT block format 1) Header Loading Loading @@ -148,7 +149,46 @@ upgrades without significantly impacting the kernel code or cluttering it with special cases. 1) Entry point for arch/powerpc 1) Entry point for arch/arm --------------------------- There is one single entry point to the kernel, at the start of the kernel image. That entry point supports two calling conventions. A summary of the interface is described here. A full description of the boot requirements is documented in Documentation/arm/Booting a) ATAGS interface. Minimal information is passed from firmware to the kernel with a tagged list of predefined parameters. r0 : 0 r1 : Machine type number r2 : Physical address of tagged list in system RAM b) Entry with a flattened device-tree block. Firmware loads the physical address of the flattened device tree block (dtb) into r2, r1 is not used, but it is considered good practise to use a valid machine number as described in Documentation/arm/Booting. r0 : 0 r1 : Valid machine type number. When using a device tree, a single machine type number will often be assigned to represent a class or family of SoCs. r2 : physical pointer to the device-tree block (defined in chapter II) in RAM. Device tree can be located anywhere in system RAM, but it should be aligned on a 64 bit boundary. The kernel will differentiate between ATAGS and device tree booting by reading the memory pointed to by r2 and looking for either the flattened device tree block magic value (0xd00dfeed) or the ATAG_CORE value at offset 0x4 from r2 (0x54410001). 2) Entry point for arch/powerpc ------------------------------- There is one single entry point to the kernel, at the start Loading Loading @@ -226,7 +266,7 @@ it with special cases. cannot support both configurations with Book E and configurations with classic Powerpc architectures. 2) Entry point for arch/x86 3) Entry point for arch/x86 ------------------------------- There is one single 32bit entry point to the kernel at code32_start, Loading
arch/arm/Kconfig +7 −0 Original line number Diff line number Diff line Loading @@ -1683,6 +1683,13 @@ endmenu menu "Boot options" config USE_OF bool "Flattened Device Tree support" select OF select OF_EARLY_FLATTREE help Include support for flattened device tree machine descriptions. # Compressed boot loader in ROM. Yes, we really want to ask about # TEXT and BSS so we preserve their values in the config files. config ZBOOT_ROM_TEXT Loading
arch/arm/include/asm/mach/arch.h +9 −0 Original line number Diff line number Diff line Loading @@ -18,6 +18,8 @@ struct machine_desc { unsigned int nr; /* architecture number */ const char *name; /* architecture name */ unsigned long boot_params; /* tagged list */ const char **dt_compat; /* array of device tree * 'compatible' strings */ unsigned int nr_irqs; /* number of IRQs */ Loading Loading @@ -47,6 +49,13 @@ struct machine_desc { */ extern struct machine_desc *machine_desc; /* * Machine type table - also only accessible during boot */ extern struct machine_desc __arch_info_begin[], __arch_info_end[]; #define for_each_machine_desc(p) \ for (p = __arch_info_begin; p < __arch_info_end; p++) /* * Set of macros to define architecture features. This is built into * a table by the linker. Loading
arch/arm/include/asm/prom.h 0 → 100644 +37 −0 Original line number Diff line number Diff line /* * arch/arm/include/asm/prom.h * * Copyright (C) 2009 Canonical Ltd. <jeremy.kerr@canonical.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #ifndef __ASMARM_PROM_H #define __ASMARM_PROM_H #ifdef CONFIG_OF #include <asm/setup.h> #include <asm/irq.h> static inline void irq_dispose_mapping(unsigned int virq) { return; } extern struct machine_desc *setup_machine_fdt(unsigned int dt_phys); extern void arm_dt_memblock_reserve(void); #else /* CONFIG_OF */ static inline struct machine_desc *setup_machine_fdt(unsigned int dt_phys) { return NULL; } static inline void arm_dt_memblock_reserve(void) { } #endif /* CONFIG_OF */ #endif /* ASMARM_PROM_H */
