I have a bootloader (BL) and an application (APP) that both live in flash. I want to communicate between the two via a shared section of RAM that is not initialized upon a reset. I previously had this working with an earlier revision of the project. The APP has since undergone a radical redesign, and when I tired to add this functionality back in, I ran into an issue.
My code builds and links fine, but if I try to run the debugger I get this error:
I have a basic understanding of linker files, but they are by and large dark arts to me. Here is my original addition where I reserve the last 4 bytes of RAM for the shared space:
...snip...
_end = . ;
_ram_end_ = ORIGIN(ram) + LENGTH(ram) - 5 ; /* MOD was -1 */
/* Define heap symbols for heap_useNewlib.c */
__HeapBase = _end;
__HeapLimit = _ram_end_;
HEAP_SIZE = __HeapLimit - __HeapBase;
/* MOD added SharedSection */
/* placing SharedSection section at given address: */
.SharedSection 0x20027FFC :
{
KEEP(*(.SharedSection)) /* keep my variable even if not referenced */
} > ram I have since changed it to this, but I was grasping at straws, and it had no effect on my error:
...snip...
_end = . ;
_ram_end_ = ORIGIN(ram) + LENGTH(ram) - 5 ; /* MOD was -1 */
/* Define heap symbols for heap_useNewlib.c */
__HeapBase = _end;
__HeapLimit = _ram_end_;
HEAP_SIZE = __HeapLimit - __HeapBase;
/* MOD added SharedSection */
/* placing SharedSection section at given address: */
.SharedSection 0x20027FFC :
{
. = ALIGN(4);
_sSharedSection = . ;
KEEP(*(.SharedSection .SharedSection.*)) /* keep my variable even if not referenced */
. = ALIGN(4);
_eSharedSection = . ;
} > ram
The map file produced by building the project has this:
0x200112e0 _end = .
0x20027ffb _ram_end_ = ((ORIGIN (ram) + LENGTH (ram)) - 0x5)
0x200112e0 __HeapBase = _end
0x20027ffb __HeapLimit = _ram_end_
0x00016d1b HEAP_SIZE = (__HeapLimit - __HeapBase)
.SharedSection 0x20027ffc 0x4 load address 0x0049a3fc
0x20027ffc . = ALIGN (0x4)
0x20027ffc _sSharedSection = .
*(.SharedSection .SharedSection.*)
.SharedSection
0x20027ffc 0x4 lib_shared/misc_core.o
0x20027ffc bootloader_shared_space
0x20028000 . = ALIGN (0x4)
0x20028000 _eSharedSection = .The load address assigned to SharedSection is the same as the address range in the error, but beyond that I am lost.
The two major linker differences between this broken version and the previous working are:
1. In the broken one the entire heap section is commented out as I now use heap_useNewlib.c in conjunction with FreeRTOS to manage the heap.
2. In the broken one there is an additional ".noinit" section used to preserve register information in the event of a hardfault and subsequent reset.
I don't know if either of these this is the root cause, but felt they should be mentioned. Neither cause any problems when the SharedSection is removed from the linker file.
The bootloader (which does not use heap_useNewlib.c) has the original addition posted above, and runs in debug just fine.
Any idea what is going on here?
Is there a better way to accomplish what I am trying to do?
