_sbrk: undefined reference to `end' problem
Wed May 28 14:00:00 GMT 2008
> In my .ld file there isn't an `end' declaration. But if I put the following code at the end of .ld file, the compilation terminate correctly, but the application does not function correctly:
> PROVIDE (end = .);
> I don't know the `end' address to insert in the declaration. Can anybody help me?
As you guessed the "end" symbol is a special one that need to be
provided by the linker script. But what you didn't know is that the
symbol needs to be placed at the lowest allocatable memory address not
occupied by the program or its data. (Try running "ld --verose" to see
how this is done with the linker's built-in default script). The
_sbrk() function in libgloss/arm/syscalls.c uses this "end" symbol as
the starting point for memory allocation.
Note: putting the "PROVIDE (end = .);" at the end of your linker script
is incorrect because presumably you have also provided the location of
the start of the stack, which is at the top of allocatable memory.
"end" needs to be that the bottom of allocatable memory.
More information about the Newlib