Open files in VS Code and Cursor / Binary, network and hardware

Analyze a linker map file in VS Code

A linker .map file says where every section, object file and symbol went, but it is thousands of lines of text. Install the free Linker Map Viewer by Zovo and click the .map file. You get FLASH and RAM bars per memory region (the same numbers as ld --print-memory-usage), sortable tables of sections, object files and symbols, a treemap, and a compare with an older build.

Free, MIT license. Extension ID zovo.zovo-linker-map-viewer, version 0.2.1. Needs VS Code 1.90.0 or newer.

Also free from Zovo: ELF Viewer & PE Viewer, VS Code Marketplace · Open VSX (Cursor, Windsurf).

Steps in VS Code

1. Install Linker Map Viewer from the Marketplace, or press Ctrl+P (Cmd+P on macOS) and run ext install zovo.zovo-linker-map-viewer.
2. Make your linker write a map: add -Wl,-Map=firmware.map,--cref to the GCC or clang link line. ESP-IDF, Zephyr, the Pico SDK and PlatformIO already write one into the build folder.
3. Click the .map file in the Explorer. The summary shows each memory region with a used and total bar.
4. Open the object file or symbol table, sort by size and filter with words or a /regex/. Double-click a row to open its source file.
5. Click "Compare..." and pick the map of an older build to see what grew, biggest first. Export the result as CSV or Markdown for a pull request.

Steps in Cursor, Windsurf or VSCodium

1. Open the Extensions view with Ctrl+Shift+X (Cmd+Shift+X on macOS).
2. Search for zovo.zovo-linker-map-viewer and click Install. Cursor, Windsurf and VSCodium install from Open VSX, where it is published as zovo/zovo-linker-map-viewer.
3. If your editor has no gallery, download the .vsix from the Open VSX page and run "Extensions: Install from VSIX...".
4. Then use it the same way as in VS Code.

What Linker Map Viewer handles

• GNU ld (gcc, arm-none-eabi-gcc, ESP-IDF, Zephyr, STM32CubeIDE, avr-gcc, RISC-V), LLVM lld (clang, Rust embedded), IAR ILINK 7.x and 8.x, and Arm Compiler armlink 5 and 6 (Keil MDK).
• Why the linker pulled in an object file ("main.o needs uart_init"), and, with --cref, which files use a symbol.
• Large maps. In the release test a 206 MB map with 1.1 million symbols showed its full summary in 3 to 5 seconds, and the editor kept working.
• A region over its size turns red. Sizes in bytes, KB or hex.

What it does not do

• GNU ld maps list global symbols without sizes. A size marked ~ runs to the next symbol and is exact only with -ffunction-sections -fdata-sections.
• Static symbols are not in GNU ld maps, so the viewer cannot list them.
• lld and Rust maps have no memory regions. The viewer reads them from memory.x or a linker script next to the map, or from a setting.
• It reads the map file only, not the ELF file or its debug info.

In JetBrains IDEs (IntelliJ IDEA, PyCharm, WebStorm, CLion and others)

• Romsight: Linker Map Analyzer. Zovo has no JetBrains plugin for map files. Romsight (35 downloads) says: "See where your firmware's flash and RAM go, from the linker .map, right in CLion." It reads GNU ld and LLVM lld maps.

Other options

• GNU Linker Map files (trond-snekvik.gnu-mapfiles, 465,256 installs, not on Open VSX). Its own description: "Syntax highlighting and symbol listing for GNU linker .map files". Not on Open VSX.
• GCC Map View (RobDerr.gcc-map-view, 2,644 installs, not on Open VSX). Its own description: "Visualize GCC linker map files (.map) and linker scripts (.ld) with a graphical memory map". Not on Open VSX.
• Linker Map Auditor (ReadyStack.linker-map-auditor, 24 installs, on Open VSX). Its own description: "Read a GNU ld .map file and see exactly which object file is eating your FLASH and RAM, and by how many bytes."
• size and nm. arm-none-eabi-size firmware.elf prints the text, data and bss totals, and arm-none-eabi-nm --size-sort -S firmware.elf lists symbols by size. They read the ELF file, not the map.

Install counts and Open VSX status were checked on 9 November 2026. Descriptions in quotes are the extensions' own.

Questions

More about Linker Map Viewer

Read the Linker Map Viewer page for every feature and setting, or the source code on GitHub.

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