Hi TigerLiu@viatech.com.cn,

On Wed, 3 Jul 2013 11:19:13 +0800, TigerLiu@viatech.com.cn wrote:

Hi, experts: I am studying u-boot latest code now. I have a question about monitor length.

1. in board_init_f() function in arch\arm\lib\board.c Gd->mon_len = _bss_end_ofs;
2. in board_init_r() function in arch\arm\lib\board.c

Monitor_flash_len = _end_ofs;

Because _end_ofs < _bss_end_ofs, so it confused me! Why need to discard some data when re-calculating monitor_in board_init_r() function.

Both functions don't compute the same thing.

GD->mon_len computes the monitor length including BSS, because it is the length in RAM at run time, which matters e.g. for relocating the monitor -- relocation copies the text and data but not the BSS.

Monitor_flash_len, as the name implies, computes the monitor length excluding BSS, because this is the length in FLASH, and BSS does not exist in the flashed image; even if we know its size at build time, BSS will only exist after relocation, just before entering board_init_r.

Best wishes,

Amicalement,