Dear Trent,
In message Pine.LNX.4.64.0810140859340.3443@t2.domain.actdsltmp you wrote:
Where is bss then, if you try to locate it beyond the end of physical memory? To the best of my understanding there are two possibilities: tool chains running on a 32 bit host will simply wrapr addresses around, i. e. start placing bss at physical address 0, which is not wrong. I don't remember eacty what you get on 64 bit hosts, but the result is not correct either.
This is where bss goes when u-boot is linked. It gets relocated to a different address in ram.
Where is defined which address it is, then?
Note that this added complexity of image layout is not shared by other architectures.
What the linker scripts *were* doing is putting bss at ADDR(.text) + 0x80000, which ends up being 0 for most boards and 0xf0000000 for some others.
Let's be careful here in our terminology. Your "most boards" is most probably not my "most boards". From the global point of view, "most boards" have a very simple layout like this:
... . = ALIGN(256); __init_begin = .; .text.init : { *(.text.init) } .data.init : { *(.data.init) } . = ALIGN(256); __init_end = .;
__bss_start = .; .bss (NOLOAD) : { *(.sbss) *(.scommon) *(.dynbss) *(.bss) *(COMMON) } _end = . ; PROVIDE (end = .); ...
BTW - this example is from a MPC85xx system...
Unless you try to make a non 512K image. Then bss might end up at 0x40000 when it should still be at 0. You could hard code the address 0, there are
The bss must NEVER, never ever be loated at 0.
The way I'm finding the location to link bss works for all mpc85xx system and for all images sizes. This lets them share the same linker script.
Are you really talking about *all* MPC85xx systems, oronlyu about the FSL boards?
And where is bss in your design at run-time, after relocation?
Have you actually tested this code? Didn't you run into such problems?
The resulting u-boot binary is exactly the same. This produces the same binaries as before using one linker script for all 85xx instead of a different one for each board.
Please define "all 85xx". I tend to doubt that.
Best regards,
Wolfgang Denk