Hi, everyone, how long no see.

Recently, I'm about to port U-boot to our board with MIPS cpu.

When I look at the function "board_init_f" in arch/mips/lib/board.c, it's found that "ulong addr, addr_sp, len = (ulong)&uboot_end - CONFIG_SYS_MONITOR_BASE;"

And I know "uboot_end" is assigned in u-boot.lds, which is also stored as a word at offset -8 in front of "in_ram" label.

What I want to know is why use the address of "uboot_end" in that equation, rather than using the value of "uboot_end" what I mean is why not go like this "len = (ulong)uboot_end - CONFIG_SYS_MONITOR_BASE".

Also, there is one more question about the usage of CONFIG_SYS_TEXT_BASE

In our <board.h>, #define CONFIG_SYS_MONITOR_BASE CONFIG_SYS_TEXT_BASE

To my knowledge, -fPIC option is used to build u-boot.bin. Doesn't it mean where u-boot runs is irrelevant to where it is linked? If yes, why CONFIG_SYS_TEXT_BASE is needed to indicate where U-boot is linked to, rather than the default linked address 0x0000_0000. I find CONFIG_SYS_TEXT_BASE is used with -Ttext linker option when generating u-boot.bin, if it is assigned.

Could you help me explain the necessity of CONFIG_SYS_TEXT_BASE existence? Or, even if CONFIG_SYS_TEXT_BASE is not assigned with a exlicit value, building u-boot.bin will actually be successful without any problems too. Does it just exist for the flexbility?

If it have to be configured, how shoud I configure it to coordinate with our memory layout ? What's the relationship between CONFIG_SYS_TEXT_BASE and CONFIG_SYS_SDRAM_BASE ？ Even with NOR FLASH or NAND FLASH address space?

By the way, when I want to use hotmail to send this mail, there comes the error: "Message rejected. No base64 encoded MIME text parts allowed."

Do you have any ideas?

Thanks in advance.