ARM Compiler toolchain Using the Linker - ARM Information Center

6.4 How to find where a symbol is placed when linking
6.4.1 Example
Getting information about images
To find where a symbol is placed in an ELF image file when linking, use the --keep=section_id
and --map options to view the image memory map. For example, if object(section) is the
section containing the symbol, enter:
armlink --keep=object(section) --map s.o --output=s.axf
The memory map shows where the section containing the symbol is placed.
Do the following:
1. Create the file s.c containing the following source code:
long long altstack[10] __attribute__ ((section ("STACK"), zero_init));
int main()
{
return sizeof(altstack);
}
2. Compile the source:
armcc -c s.c -o s.o
3. Link the object s.o, keeping the STACK symbol and displaying the image memory map:
armlink --keep=s.o(STACK) --map s.o --output=s.axf
4. Locate the STACK symbol in the output, for example:
...
Execution Region ER_RW (Base: 0x000081c8, Size: 0x00000000, Max: 0xffffffff, ABSOLUTE)
**** No section assigned to this execution region ****
Execution Region ER_ZI (Base: 0x000081c8, Size: 0x000000b0, Max: 0xffffffff, ABSOLUTE)
Base Addr Size Type Attr Idx E Section Name Object
0x000081c8 0x00000060 Zero RW 42 .bss libspace.o(c_4.l)
0x00008228 0x00000050 Zero RW 2 STACK s.o
This shows that the stack is placed in execution region ER_ZI.
6.4.2 See also
Tasks
• Using fromelf to find where a symbol is placed in an executable ELF image on page 3-12.
Reference
Compiler Reference:
• -c on page 3-31
• -o filename on page 3-152.
Linker Reference:
• --keep=section_id on page 2-89
• --map, --no_map on page 2-108
• --output=file on page 2-114.
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