ARM Linux - Developer

摘自： http://www.arm.linux.org.uk/ 作者：Russell King

高速程序代码下载速度200KBytes/S以上、内置对于GDB Remote Serial Protocol协议支持、FoxICE仿真器完美支持GDB 的 File IO扩展协议、免费赠送Eclipse for ARM V 3.2.1集成开发环境、支持Nand Flash( S3C2410或 S3C2440可任 选一种 )的烧写，支持超低电压的处理器调试, 目标范围为：0.65 ～ 5.5V 详细信息 >>

• Setup the kernel tagged list
  Existing boot loaders: OPTIONAL, HIGHLY RECOMMENDED
  New boot loaders: MANDATORY
  
  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 has the size field set to '2' (0x00000002). The ATAG_NONE must set the size field to zero.
  
  Any number of tags can be placed in the list. It is undefined whether a repeated tag appends to the information carried by the previous tag, or whether it replaces the information in its entirety; some tags behave as the former, others the latter.
  
  The boot loader must pass at a minimum the size and location of the system memory, and root filesystem location. Therefore, the minimum tagged list should look:
  
  The tagged list should be stored in system RAM.
  
  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.
  
• Calling the kernel image
  Existing boot loaders: MANDATORY
  New boot loaders: MANDATORY
  
  There are two options for calling the kernel zImage. If the zImage is stored in flash, and is linked correctly to be run from flash, then it is legal for the boot loader to call the zImage in flash directly.
  
  The zImage may also be placed in system RAM (at any location) and called there. Note that the kernel uses 16K of RAM below the image to store page tables. The recommended placement is 32KiB into RAM.
  
  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.
  • CPU mode
    • All forms of interrupts must be disabled (IRQs and FIQs.)
    • The CPU must be in SVC mode. (A special exception exists for Angel.)
  • Caches, MMUs
    • The MMU must be off.
    • Instruction cache may be on or off.
    • Data cache must be off and must not contain any stale data.
  • Devices
    • DMA to/from devices should be quiesced.
    • The boot loader is expected to call the kernel image by jumping directly
      to the first instruction of the kernel image.

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