Analyze GNU/Clang/IAR ld’s linker map, based on visual version .
Works best with -ffunction-sections -fdata-sections and statically linked code (e.g. for bare-metal embedded systems).
Note: -flto merges code across .o files and make it difficult to analyze.
$ pip install .
$ linkermap --version
0.5.0$ linkermap --help (or python linker-map.py --help)
usage: linkermap [-h] [-v] [-s EXTRA_SECTIONS] [-j] [-f FILTERS] [-m] [-S SORT] [-q] [-d OUT_DIR] [-V] map_file
Analyze GNU/Clang/IAR ld linker map.
positional arguments:
map_file Path to the linker map file to analyze.
options:
-h, --help show this help message and exit
-v, --verbose Print symbols within file.
-s EXTRA_SECTIONS, --section EXTRA_SECTIONS
Additional section name to include; repeat for multiple sections.
-j, --json Write JSON summary next to the map file.
-f FILTERS, --filter FILTERS
Only include object files whose path contains this substring (can be repeated).
-m, --markdown Write Markdown table next to the map file.
-S SORT, --sort SORT Sorting: size-, size+, name-, name+ (default name+). Applies to stdout and markdown.
-q, --quiet Suppress standard summary output.
-d OUT_DIR, --dir OUT_DIR
Directory to write JSON/Markdown outputs (default: alongside map file).
-V, --version show program's version number and exit$ linkermap --sort=size- cdc_msc.elf.map
File | .text .data .bss Total
------------------------------------------------------------------------------------
msc_disk.o | 8192 1 313 8506
usbd.o | 24 257 2820 3101
dcd_nrf5x.o | 0 220 2678 2898
msc_device.o | 0 576 2050 2626
libc.a | 1072 33 696 1801
cdc_device.o | 0 312 1044 1356
tusb_fifo.o | 0 0 1142 1142
nrfx_uarte.o | 0 36 800 836
usbd_control.o | 0 84 516 600
gcc_startup_nrf52840_asm.o | 0 0 572 572
system_nrf52840.o | 4 0 568 572
usb_descriptors.o | 24 64 276 364
nrfx_power.o | 0 13 330 343
family.o | 8 4 274 286
main.o | 4 5 188 197
tusb.o | 0 0 176 176
crt0.o | 0 0 124 124
crtbegin.o | 8 25 64 97
libc_nano.a | 0 0 96 96
crtn.o | 0 0 16 16
crti.o | 0 0 8 8
crtend.o | 0 0 4 4
libnosys.a | 0 0 4 4
SUM | 25725 9336 1630 14759
$ linkermap -sort=size- -v cdc_msc.elf.map
File | .text .data .bss Total
------------------------------------------------------------------------------------
usbd_control.o | 0 84 516 600
-------------- |--------------------------------
usbd_control_xfer_cb | 0 0 208 208
tud_control_xfer | 0 0 112 112
.text._data_stage_xact | 0 0 92 92
.bss._usbd_ctrl_buf | 0 64 0 64
tud_control_status | 0 0 48 48
usbd_control_set_request | 0 0 28 28
.bss._ctrl_xfer | 0 20 0 20
usbd_control_reset | 0 0 16 16
usbd_control_set_complete_callback | 0 0 12 12
------------------------------------------------------------------------------------
gcc_startup_nrf52840_asm.o | 0 0 572 572
-------------------------- |--------------------------------
__isr_vector | 0 0 512 512
Reset_Handler | 0 0 60 60
------------------------------------------------------------------------------------
system_nrf52840.o | 4 0 568 572
----------------- |--------------------------------
SystemInit | 0 0 464 464
.text.nrf52_errata_36 | 0 0 60 60
.text.nrf52_errata_98 | 0 0 40 40
SystemCoreClock | 4 0 0 4
.rodata.CSWTCH.6 | 0 0 4 4
------------------------------------------------------------------------------------
usb_descriptors.o | 24 64 276 364
----------------- |--------------------------------
desc_fs_configuration | 0 0 98 98
tud_descriptor_string_cb | 0 0 88 88
.bss._desc_str | 0 64 0 64
.rodata.str1.1 | 0 0 54 54
string_desc_arr | 24 0 0 24
desc_device | 0 0 18 18
tud_descriptor_device_cb | 0 0 8 8
tud_descriptor_configuration_cb | 0 0 8 8
.rodata.__compound_literal.0 | 0 0 2 2
------------------------------------------------------------------------------------
$ linkermap --sort=size- -m cdc_msc.elf.map
# Linker Map Summary
| File | .text | .rodata | .data | .bss | Total |
|:--------------------------|--------:|----------:|--------:|-------:|--------:|
| msc_disk.o | 300 | 13 | 8192 | 1 | 8506 |
| usbd.o | 2718 | 48 | 24 | 245 | 3035 |
| dcd_synopsys.o | 2578 | 0 | 0 | 143 | 2721 |
| msc_device.o | 2050 | 0 | 0 | 576 | 2626 |
| cdc_device.o | 1044 | 0 | 0 | 312 | 1356 |
| stm32f4xx_hal_rcc.o | 1316 | 0 | 0 | 0 | 1316 |
| tusb_fifo.o | 1198 | 0 | 0 | 0 | 1198 |
| libgcc.a | 760 | 0 | 0 | 0 | 760 |
| family.o | 564 | 0 | 0 | 68 | 632 |
| usbd_control.o | 516 | 0 | 0 | 84 | 600 |
| stm32f4xx_hal_gpio.o | 414 | 0 | 0 | 0 | 414 |
| usb_descriptors.o | 104 | 172 | 24 | 64 | 364 |
| stm32f4xx_hal_uart.o | 326 | 0 | 0 | 0 | 326 |
| main.o | 188 | 0 | 4 | 5 | 197 |
| libc_nano.a | 184 | 0 | 0 | 0 | 184 |
| tusb.o | 176 | 0 | 0 | 0 | 176 |
| stm32f4xx_hal_cortex.o | 144 | 0 | 0 | 0 | 144 |
| stm32f4xx_hal.o | 84 | 0 | 5 | 4 | 93 |
| startup_stm32f411xe_asm.o | 82 | 0 | 0 | 0 | 82 |
| system_stm32f4xx.o | 28 | 24 | 4 | 0 | 56 |
| SUM | 14774 | 257 | 8253 | 1502 | 24786 |extra sections & JSON/Markdown output
Enable JSON/Markdown outputs with flags; files are written beside the map using the map’s basename:
$ linkermap -s .fastcode -s .itcm -j -m build/firmware.mapThe Markdown table includes a final SUM row with totals across all files. JSON and Markdown are saved as <map_file>.json / <map_file>.md in the same directory as the map file. Outputs follow the -v/--verbose flag: non-verbose shows per-file section totals; verbose lists each symbol per file with section names as columns plus a per-symbol Total column, sorted by size, and a per-file SUM row.
In verbose mode the Markdown file groups symbols under each file as separate tables for easier browsing. Use -f/--filter (repeatable) to include only object files whose path contains given substrings.
