MSM8x25 android开发流程分析

一、boot分析，编译完成后生成以下文件amss.bin来源于amss.mbn，就是modem通讯协议模块。qcsbl.bin来源于qcsbl.mbn -->qcsbl boot --》qcsbl.S、qcsbl——mc.c和qcsbl.sclqcsbl主要工作是：1、继续对硬件进行设置；2、从nand中，查找出激活的多镜像块；3、加载oemsbl镜像的头信息块4、鉴定oemsbl镜像的合法性；5、运行加载好的oemsbl镜像模块；6、加载amss镜像的头信息块；7、加载amss镜像；7、鉴定amss镜像合法性，若需要的话。8、把控制权交给amss代码。总结如下：根据硬件特性，进一步对硬件和外围设备进行初始化，比如usb、mmu、bus、mpu等模块；下载过程的实现：oemsbl部分来配合烧写的；加载arm11的emmc_appsboot,唤起arm11.代码分析：qcsbl.s

;============================================================================
;
;                             MODULE EXPORTS
;
;============================================================================

; Export the external symbols that are referenced in this module.
EXPORT qcsbl_loop_here

; Export the symbols __main and _main to prevent the linker from
; including the standard runtime library and startup routine.
EXPORT   __main
EXPORT   _main

;============================================================================
;
;                             MODULE DATA AREA
;
;============================================================================

;--------------------------------------------------------------------------
; Data area is in IRAM and location must be defined in scatter load
; file.  Data area starts at the top of IRAM.
;--------------------------------------------------------------------------
PRESERVE8
AREA    QCSBL_VECTOR_TABLE, DATA, READWRITE

;--------------------------------------------------------------------------
; Exception vectors table located at the top of IRAM.  This is initialized
; to the QCSBL exception handlers.  This region will be copied into IRAM
; to replace the vectors which were used by the PBL.
;--------------------------------------------------------------------------

unused_reset_vector
DCD     0x00000000
undefined_instruction_vector
DCD     qcsbl_undefined_instruction_nested_handler
swi_vector
DCD     qcsbl_swi_c_handler
prefetch_abort_vector
DCD     qcsbl_prefetch_abort_nested_handler
data_abort_vector
DCD     qcsbl_data_abort_nested_handler
reserved_vector
DCD     qcsbl_reserved_c_handler
irq_vector
DCD     qcsbl_irq_c_handler
fiq_vector
DCD     qcsbl_fiq_c_handler

oemsbl.s

AREA    OEMSBL_VECTOR_TABLE, DATA, READWRITE
unused_reset_vector
DCD     0x00000000
undefined_instruction_vector
DCD oemsbl_undefined_instruction_nested_handler
swi_vector
DCD oemsbl_swi_c_handler
prefetch_abort_vector
DCD oemsbl_prefetch_abort_nested_handler
data_abort_vector
DCD oemsbl_data_abort_nested_handler
reserved_vector
DCD oemsbl_reserved_c_handler
irq_vector
DCD oemsbl_irq_c_handler
fiq_vector
DCD oemsbl_fiq_c_handler

qcsbl.scloemsbl.scloemsbl_mc.coemsbl_aarm_boot.coemsbl.bin 作用：加载oemsbl镜像 ，来源于oemsbl.S、oemsbl_mc.c、oemsbl_aarm_boot.c和oemsbl.scl 位于/modem/modem_proc/core/boot/secboot/oemsbl/下oemsblhd.bin作用：加载oemsbl镜像的头信息块，（mibib格式）emmc_appsboot.bin 来源于emmc_appsboot.mbn，这个就是bootloader，就是android端的启动代码。boot.img不是bootloader.而是kernel和ram disksystem.img.etx4 是android的root fs。启动过程如下：

AREA    QCSBL_ENTRY, CODE, READONLY
CODE32
ENTRY

__main
_main
...
...

ldr    r1, =qcsbl_main_ctl
blx    r1

二、amss修改三、android启动