Lines Matching +full:in +full:- +full:kernel
7 The following documentation is relevant to 2.4.18-rmk6 and beyond.
9 In order to boot ARM Linux, you require a boot loader, which is a small
10 program that runs before the main kernel. The boot loader is expected
11 to initialise various devices, and eventually call the Linux kernel,
12 passing information to the kernel.
20 4. Setup the kernel tagged list.
22 6. Call the kernel image.
26 ---------------------------
32 kernel will use for volatile data storage in the system. It performs
33 this in a machine dependent manner. (It may use internal algorithms
35 the RAM in the machine, or any other method the boot loader designer
40 -----------------------------
46 target. This allows the kernel serial driver to automatically detect
47 which serial port it should use for the kernel console (generally
51 option to the kernel via the tagged lists specifying the port, and
52 serial format options as described in
54 Documentation/admin-guide/kernel-parameters.rst.
58 --------------------------
61 New boot loaders: MANDATORY except for DT-only platforms
67 value to the kernel. (see linux/arch/arm/tools/mach-types). This
68 should be passed to the kernel in register r1.
70 For DT-only platforms, the machine type will be determined by device
75 ------------------
81 passing configuration data to the kernel. The physical address of the
82 boot data is passed to the kernel in register r2.
84 4a. Setup the kernel tagged list
85 --------------------------------
87 The boot loader must create and initialise the kernel tagged list.
93 Any number of tags can be placed in the list. It is undefined
95 previous tag, or whether it replaces the information in its
102 +-----------+
103 base -> | ATAG_CORE | |
104 +-----------+ |
106 +-----------+ |
108 +-----------+ v
110 The tagged list should be stored in system RAM.
112 The tagged list must be placed in a region of memory where neither
113 the kernel decompressor nor initrd 'bootp' program will overwrite
114 it. The recommended placement is in the first 16KiB of RAM.
117 -------------------------
121 dtb format is documented in Documentation/devicetree/booting-without-of.txt.
122 The kernel will look for the dtb magic value of 0xd00dfeed at the dtb
128 placed in a region of memory where the kernel decompressor will not
130 by the kernel's low-memory mapping.
135 ------------------
140 If an initramfs is in use then, as with the dtb, it must be placed in
141 a region of memory where the kernel decompressor will not overwrite it
142 while also with the region which will be covered by the kernel's
143 low-memory mapping.
149 6. Calling the kernel image
150 ---------------------------
155 There are two options for calling the kernel zImage. If the zImage
156 is stored in flash, and is linked correctly to be run from flash,
157 then it is legal for the boot loader to call the zImage in flash
160 The zImage may also be placed in system RAM and called there. The
161 kernel should be placed in the first 128MiB of RAM. It is recommended
162 that it is loaded above 32MiB in order to avoid the need to relocate
166 When booting a raw (non-zImage) kernel the constraints are tighter.
167 In this case the kernel must be loaded at an offset into system equal
168 to TEXT_OFFSET - PAGE_OFFSET.
170 In any case, the following conditions must be met:
172 - Quiesce all DMA capable devices so that memory does not get
176 - CPU register settings
178 r1 = machine type number discovered in (3) above.
179 r2 = physical address of tagged list in system RAM, or
180 physical address of device tree block (dtb) in system RAM
182 - CPU mode
186 CPU must be in SVC mode. (A special exception exists for Angel)
189 entered in HYP mode in order to enable the kernel to make full use of
191 unless the virtualisations are already in use by a pre-installed
194 If the kernel is not entered in HYP mode for any reason, it must be
195 entered in SVC mode.
197 - Caches, MMUs
202 If the kernel is entered in HYP mode, the above requirements apply to
203 the HYP mode configuration in addition to the ordinary PL1 (privileged
204 kernel modes) configuration. In addition, all traps into the
207 possible. Except for entering in HYP mode, the system configuration
208 should be such that a kernel which does not include support for the
211 - The boot loader is expected to call the kernel image by jumping
212 directly to the first instruction of the kernel image.
215 made in ARM state, even for a Thumb-2 kernel.
218 Cortex-M class CPUs, the entry must be made in Thumb state.