uboot start the first phase

  s5pv210 irom the code reading sd (mmc channel 3) 16kB (uboot first stage code) to 0xd0020010 iram after the verification performed by starting

The first instruction located cpu / s5pc11x / start.S

1 _start: b reset (line 57)

2, line 149 is provided svc mode disables irq bit CPU and fiq

3200 ~ 204 disposed cache

4209 ~ 211 and TLB provided icache

5216 ~ 221 disposed cp15 prohibition of c1 and cache mmu

6225 ~ 227 reads boot information (the information will start CortexA8 retained in 0xE0000004)

7243 - 278 we set the start flag stored in the register

8284 ~ 286 disposed stack

9 288 bl lowlevel_init (located on board / samsung / x210)

10 46 ~ 52 (lowlevel_init) according to the reset state transition, a cold start is executed sequentially

11 61 ~ 64 (lowlevel_init) Off Watchdog

12 100 ~ 104 (lowlevel_init) on the electrical signal latch

13 110 ~ 115 (lowlevel_init) uboot determine the current or in the DDR sram

14 118 bl system_clock_init clock system initialization

15 121 bl mem_ctrl_asm_init initialize the memory

16 125 bl uart_asm_init serial printer initialization 'O'

17151 ~ 156 print 'K' returns in start.s

18292 ~ 294 latches the electrical signal 12 and the same steps

19297 ~ 299 set up the stack 0x33e00000

20 313 ~ 318 if BL1 copy to SD / MMC CH2 jump mmcsd_boot, we are here

21 349 bl movi_bl2_copy uboot will be copied to memory 0x33e00000

22 361 ~ 371 and the TTB field access is provided (page table base address)

   The one-page table trillion mapping effectively mapped c0000000-d0000000 30000000-40000000 256MB 3G-3.25G

23374 ~ 381 open mmu

24387 ~ 396 set up the stack again

25400 ~ 411 bss clear long-jump function to start_armboot

 

 

 

 

 

 

 

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Origin www.cnblogs.com/genshu123/p/11798773.html