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Booting sequence of Linux2.6 on 32-bits PowerPC
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_start:

__start:
Save input parameters passing from u-boot
early_init:
relocate global variables
memset_io: zero BSS section
identify_cpu: identify current CPU type. cur_cpu_spec contains index in cpu_specs[]
do_cpu_ftr_fixups: fill sections special for the CPU type
mmu_off: turn off MMU
__after_mmu_off:
clear_bats: clear BATs
flush_tlbs: Invalid all TLB entries
initial_bats: 8M for instructions and data through xBAT0 individualy (totally 16M)
reloc_offset: code relocation
call_setup_cpu:
__setup_cpu_750: Enable Data/instruction cache through HID0
relocate_kernel: Move kernel code from current running address to KERNELBASE (physical address 0)
turn_on_mmu: turn on MMU through MSR

start_here:
Save virtual address of current task structure to GPR2
Save physical address of current thread structure to SPR3
Setup stack pointer (GPR1)
machine_init:
copy command line from CONFIG_CMDLINE to cmd_line
platform_init:
parse_bootinfo: parse board information from u-boot
relocate_nodes: relocate device tree
finish_device_tree: initialize the device tree
MMU_init:
MMU_setup: looking for TLB/BAT options and maximum memory size from command line
MMU_init_hw: Setup hash table at top end of physical memory
mapin_ram: mapping all memory from KERNELBASE
mmu_context_init: initialize context management staff
load_up_mmu: initialize BATs and load settings of HW page tables into registers (E.g SDR)