gem5

Mac · Linux · Self-hosted

Freedom report

Two barsScore 6.4

Free tierA free tier is on its own pricing page
Open codeNo open-source code on record
Runs widely2 of 6 device platforms
DocumentedPlans, terms and facts published

gem5 is ranked #18 of 37 in emulator software on Freedom251. It runs on Linux, macOS, Self-hosted. There is a free plan.

gem5 plans and pricing

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gem5 Free Open-source computer-system architecture simulator gem5.org · 3 Oct 2026

Compared on emulator software

Free plan: Yes
Supported targets: Alpha, ARM, MIPS, POWER, RISC-V, SPARC, x86
Host operating systems: Linux
Hardware acceleration: Yes
Snapshots and restore: Yes
Debugging tools: Yes
Network simulation: Yes
Automation access: Yes

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The record

Purpose: gem5 is a modular platform for computer-system architecture research, covering system-level architecture and processor microarchitecture.
Users: The project says gem5 is used in academia, industry research, and teaching.
CPU models: gem5 provides four interpretation-based CPU models and a KVM-based CPU model for faster simulation.
Memory modeling: Its event-driven memory system includes caches, crossbars, snoop filters, and a DRAM controller model.
Instruction sets: The about page lists Alpha, ARM, SPARC, MIPS, POWER, RISC-V, and x86 ISA support.
Simulation modes: gem5 supports full-system simulation and application-only execution using Linux emulation.
SystemC integration: gem5 can run as a thread inside the SystemC event kernel, and provides a wrapper for SystemC Transaction Level Modelling.
GPU model: gem5 includes a NoMali GPU model compatible with the Linux and Android GPU driver stack; it does not produce visual output.
License: The simulator is released under a Berkeley-style open-source license, with portions derived from other sources subject to their original licenses.
Reproducibility: gem5art provides Python modules for artifacts, reproducibility, and testing, and can store experiment inputs and results in a database.
Build platforms: The project tests builds on Ubuntu 22.04 and 24.04; it says other Linux-based operating systems can work with the required dependencies installed.
Build requirements: The building guide lists GCC version 10 or later, up to version 13, and says Clang is also supported.
Support: Users can ask questions through GitHub Discussions, Slack, or mailing lists; bug reports should be submitted through GitHub issues.
Known support limit: For gem5 v25.0, the documentation says only the listed Ubuntu 22.04/kernel 5.15 and Ubuntu 24.04/kernel 6.8.12 combinations are regularly tested and supported.
Price from: Free

Where it ranks on Freedom251

Best Emulator Software in 2026#18 of 37

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Sources

gem5.org· checked 3 Oct 2026
gem5.org/about/· checked 3 Oct 2026
gem5.org/documentation/gem5art/introduction· checked 3 Oct 2026
gem5.org/documentation/general_docs/building· checked 3 Oct 2026
gem5.org/ask-a-question/· checked 3 Oct 2026
gem5.org/documentation/general_docs/fullsystem/s· checked 3 Oct 2026