Linker Map Auditor - FLASH & RAM budget for GNU ld

region 'RAM' overflowed by 680 bytes. The linker tells you that you lost. It never tells you who took it.

Open the .map file your build already wrote and get the answer in one command:

REGION              USED        SIZE        FREE     USED%  STATUS
FLASH             15,088      65,536      50,448     23.0%  ok
RAM                8,872       8,192        -680    108.3%  OVER by 680 B

RAM - top spenders (8.66 KiB used)
       4,096  uart.o                              .bss.uart_rx_buf
       2,048  log.o                               .bss.log_pool
         640  app.o                               .data.cfg, COMMON
         448  libhal.a(stm32f4xx_hal.o)           .bss.hal_state
         100  main.o                              .data.tick
       1,540  (not attributed to an input section) (padding, heap/stack reservations)

That is the whole free feature. No key, no watermark, no file limit.

Install and run

1. Build with a map file: arm-none-eabi-gcc ... -Wl,-Map=build/app.map
2. Open build/app.map in VS Code.
3. Command Palette -> Linker Map: Analyze this linker map

The status bar then shows FLASH 23% RAM 108%. Click it to reopen the report.

What it reads

Any GNU ld map file: arm-none-eabi-ld, riscv64-unknown-elf-ld, avr-ld, msp430-ld, and the maps written by STM32CubeIDE, MCUXpresso, Zephyr and PlatformIO. It parses the Memory Configuration block for real region origins and lengths, follows section names that ld wraps onto two lines, resolves archive members like libhal.a(stm32f4xx_hal.o), and counts *fill* padding.

Two details most hand-written scripts get wrong, and this does not:

• .data is charged twice. Its variables live in RAM, its initialiser sits in FLASH. Both are real.
• Debug sections are charged to nothing. .debug_info, .comment and .ARM.attributes sit at address 0 in no region and never reach the device, so they are never counted as growth.

Whatever no input section claims - alignment padding, _Min_Heap_Size, _Min_Stack_Size - is reported on its own line rather than silently dropped, so the columns add up to the region total exactly.

Free vs licensed

The free side answers "what is in this build" and it answers it completely. The licence answers the different question "what changed since the build that fit":

FLASH: 14,064 -> 15,088  (+1,024 B)
RAM:    6,824 ->  8,872  (+2,048 B)  OVER by 680 B
  ^ this build is the one that stopped fitting.

What moved:
  +2,048 B  RAM  uart.o  (changed)
  +1,024 B  FLASH  libc_nano.a(lib_a-printf.o)  (changed)

$29 once - one licence key per person or team seat - 7-day full refund. A freelance embedded engineer averages $103/hr (contractrates.fyi, 2026); this is about 17 minutes of one.

Full workspace sweep and report: free for 7 days from your first sweep, then a licence key.

Get the full version - $29

Settings

Commands

Your map file is parsed locally. Nothing is uploaded. The only network call the extension ever makes is the licence check to api.polar.sh, and only when you use a licensed command.