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memap - Static Memory Map Analysis

Introduction

memap is a simple utility useful to display static memory information required by mbed applications. This information is produced by analysing the memory map file previously generated by your toolchain.

Note: this tool is showing static RAM usage and the total size of allocated heap and stack space defined at compile time, not the actual heap and stack usage (which may be different depending on your application).

Using memap
Information on memory sections
Current support
Known problems

Using memap

memap is automatically invoked after an mbed build finishes succesfully. But it's also possible to manually run the program with different command line options, for example:

$> python memap.py
usage: memap.py [-h] -t TOOLCHAIN [-o OUTPUT] [-e EXPORT] [-v] file

Memory Map File Analyser for ARM mbed version 0.3.11

positional arguments:
  file                  memory map file

optional arguments:
  -h, --help            show this help message and exit
  -t TOOLCHAIN, --toolchain TOOLCHAIN
                        select a toolchain used to build the memory map file
                        (ARM, GCC_ARM, IAR)
  -o OUTPUT, --output OUTPUT
                        output file name
  -e EXPORT, --export EXPORT
                        export format (examples: 'json', 'csv-ci', 'table':
                        default)
  -v, --version         show program's version number and exit

Example:

$> python memap.py GCC_ARM\myprog3.map -t GCC_ARM

+----------------------------+-------+-------+------+
| Module                     | .text | .data | .bss |
+----------------------------+-------+-------+------+
| Fill                       |   170 |     0 | 2294 |
| Misc                       | 36282 |  2220 | 2152 |
| core/hal                   | 15396 |    16 |  568 |
| core/rtos                  |  6751 |    24 | 2662 |
| features/FEATURE_IPV4      |    96 |     0 |   48 |
| frameworks/greentea-client |   912 |    28 |   44 |
| frameworks/utest           |  3079 |     0 |  732 |
| Subtotals                  | 62686 |  2288 | 8500 |
+----------------------------+-------+-------+------+
Allocated Heap: 65540 bytes
Allocated Stack: 32768 bytes
Total Static RAM memory (data + bss): 10788 bytes
Total RAM memory (data + bss + heap + stack): 109096 bytes
Total Flash memory (text + data + misc): 66014 bytes

Information on memory sections

Find here extended description on the multiple memory sections shown in the previous table.

text: is where the code application and constants are located in Flash
data: non-zero initialized variables; allocated in both RAM and Flash memory (variables are initialized in RAM at run time from Flash)
bss: uninitialized data allocated in RAM, or variables initialized to zero
heap: dynamic allocated memory defined at build time, usually used by malloc, etc, in RAM
stack: used to store local data, temporary data when branching to a subroutine and context switch info; it's considered dynamic allocated memory region in RAM defined at build time

On the other hand, there are other entries which do not correspond to modules directly and require a bit of clarification:

Fill: this entry represents the bytes in multiple sections (RAM and Flash) that the toolchain has filled with zeros because requires subsequent data or code to be aligment appropriately in memory
Misc: it mainly represents helper libraries introduced by the toolchain (e.g. libc) but there might be other modules not part of mbed

Current support

memap has been tested on Windows 7, Linux and Mac.

Supported map files generated by the following toolchains: GCC_ARM, ARM (ARM Compiler 5) and IAR.

Known problems & New features

This utility is considered 'Alpha' quality at the moment. Please note, the information generated by this utility may not be fully accurate and may vary from one toolchain to another.

If you are seeing problems or would like new features to be added then please raise a ticket on GitHub and use [memap] in the title.

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