A guide to choosing and configuring program linkers, which combine compiled code into an executable, and link-time optimisation (LTO), which improves code across modules during linking.

Use it when selecting GNU ld, gold, or lld, setting linker flags, writing linker scripts, managing symbol visibility, or enabling LTO.

It helps explain link-time errors such as missing or duplicate symbols, link order problems, and the trade-offs of enabling LTO.

linkers-lto — Skill for Claude Code and Codex by mohitmishra786

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add mohitmishra786/low-level-dev-skills --skill linkers-lto

Clone the repo

git clone --depth 1 https://github.com/mohitmishra786/low-level-dev-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/mohitmishra786/low-level-dev-skills/linkers-lto/github.svg)](https://agentmods.dev/skills/mohitmishra786/low-level-dev-skills/linkers-lto)

Your own site

<a href="https://agentmods.dev/skills/mohitmishra786/low-level-dev-skills/linkers-lto"><img src="https://agentmods.dev/badge/skills/mohitmishra786/low-level-dev-skills/linkers-lto/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/mohitmishra786/low-level-dev-skills/linkers-lto"><img src="https://agentmods.dev/badge/skills/mohitmishra786/low-level-dev-skills/linkers-lto.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 94 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,637 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

Socket pass 18 Mar 2026
Snyk pass 21 Feb 2026
NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00094	$0.01637
Opus 5	$0.00047	$0.00818
Sonnet 5	$0.00019	$0.00327
Haiku 4.5	$0.00009	$0.00164

Measured 11d ago against content hash 07db69a80336, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

linkers-lto scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/binaries/linkers-lto/SKILL.md · 179 lines

How it starts

The opening of the file, as written. The whole thing — 179 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Linkers and LTO

Purpose

Guide agents through linker selection, common linker flags, link-order issues, LTO setup, and symbol-visibility management.

Triggers

"I'm getting undefined reference at link time"
"How do I enable LTO for a real project?"
"Which linker should I use: ld, gold, or lld?"
"How do I reduce binary size with --gc-sections?"
"How do I write or understand a linker script?"
"I have duplicate symbol or weak symbol issues"

Workflow

1. Linker selection

Linker	Invocation	Strengths
GNU ld (BFD)	default on Linux	Universal, stable
gold	`-fuse-ld=gold`	Faster than ld for C++; supports LTO plugins
lld (LLVM)	`-fuse-ld=lld`	Fastest, parallel, required for Clang LTO

# Use lld with GCC or Clang
gcc -fuse-ld=lld -o prog ...
clang -fuse-ld=lld -o prog ...

# Check which linker is used
gcc -v -o prog main.c 2>&1 | grep 'Invoking'

2. Essential linker flags

# Pass linker flags via compiler driver:
# -Wl,flag1,flag2   (comma-separated, no spaces)
# -Wl,flag1 -Wl,flag2  (separate -Wl options)

gcc main.c -o prog \
  -Wl,-rpath,/opt/mylibs/lib \     # runtime library search path
  -Wl,--as-needed \                 # only link libraries that are actually used
  -Wl,--gc-sections \               # remove unused sections (requires -ffunction-sections -fdata-sections)
  -Wl,-z,relro \                    # mark relocations read-only after startup
  -Wl,-z,now \                      # resolve all symbols at startup (full RELRO)
  -L/opt/mylibs/lib -lfoo

3. Link order matters (GNU ld)

GNU ld processes archives left-to-right. A library must come after the objects that need it.

# Wrong: libfoo provides symbols needed by main.o
gcc main.o -lfoo libdep.a -o prog   # can fail if libdep.a needs libfoo

# Correct: dependencies after dependents
gcc main.o -lfoo -ldep -o prog

# If there are circular deps between archives:
gcc main.o -Wl,--start-group -lfoo -lbar -Wl,--end-group -o prog
# --start-group/--end-group: repeat search until no new symbols resolved

Read the full file on GitHub · 179 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

references/flags.md 7.2 KB

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

11d ago First seen · 179 lines · 94 tokens per session scan A 07db69a80336

Subscribe to this mod's changes

linkers-lto is a skill published in the GitHub repository mohitmishra786/low-level-dev-skills (202 stars, last pushed 2mo ago), licensed MIT. It adds 94 tokens to every session and 1,637 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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