An automated hardware-design flow is only as reliable as its least reliable dependency. For us, that dependency turned out to be a license. This post shows how to run your own Gowin floating license server on Linux. It takes about an hour once you know the three things the documentation doesn’t tell you.
Why it mattered
Our group runs an agentic flow in which an LLM writes Verilog and a pipeline of deterministic gates checks it: lint, simulation bit-exact against a reference model, then synthesis and place-and-route on a Gowin GW5AST-138 (the chip on the Sipeed Tang Mega 138K). The method is described in our APSIPA ASC 2026 paper [1]. A flow like this runs unattended for hours. If the synthesis tool can’t get a license at 2 a.m., the run doesn’t fail loudly. It just stops producing results.
Like many Tang board users, we had been using a shared online license server. It is a generous free service and it got us started. But one day gw_sh printed:
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The license expires in 5 days.
The countdown belonged to the shared server, not to us. A research cluster needs something it controls.
What you need
| Item | Where it comes from |
|---|---|
A floating license file (gowin_E_<MAC>_floating.lic) | Gowin’s “Apply License” form, free for academic use |
| Gowin License Server for Linux | Gowin’s documentation database (member login required) |
| A Linux machine with a stable MAC address | the license is locked to it |
| Gowin EDA V1.9.8.01 or later on the clients | we tested V1.9.12.02 |
1. Apply for the license
On the Gowin website, open Support → Apply License and choose:
- Type of License: Shared (Floating for license Server)
- Operating System: Linux
- PC MAC Address: the MAC of the machine that will run the server (
cat /sys/class/net/<nic>/address)
Our reply came within a day: a 10-seat floating license, valid for one year. (Gowin later raised it to 50 seats; see the lessons below.) Check it before going further:
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grep -E "MODE|HOST_ID|EXP_DATE|COUNT" gowin_E_*_floating.lic
# MODE = FLOATING
# HOST_ID = <your MAC, no colons, upper case>
2. Pick the right server package
Search the documentation database for “license server for linux”. You will find three packages, and the names are confusing:
| Listing | Use it? |
|---|---|
| For Gowin_V1.9.8 and earlier version (2022, ZIP) | No: old license format |
| For Gowin_V1.9.8.01 and Higher version (30/12/2024, GZ) | Yes: matches the gowin_E_*.lic format; works with V1.9.12.02 |
| For Gowin_V1.9.12.01 and earlier version (2.2E, 31/12/2025, GZ) | Backup, if the one above ever rejects a newer EDA |
The package (Gowin_LicenseServer_V2.1_linux.tar.gz) contains one program, bin/license_server, plus libraries. There is no README.
3. Install, and avoid the crash
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mkdir -p /opt/gowin-license && cd /opt/gowin-license
tar xzf Gowin_LicenseServer_V2.1_linux.tar.gz
cp gowin_E_*_floating.lic . && chmod 600 gowin_E_*_floating.lic
Gotcha #1. If you put the package’s own lib/ folder on LD_LIBRARY_PATH, the server dies at once:
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symbol lookup error: .../lib/libpthread.so.0: undefined symbol: __libc_dl_error_tsd, version GLIBC_PRIVATE
The package ships its own copy of libpthread, which clashes with a modern glibc. Use only bin/, which holds the Qt libraries the server actually needs:
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S=/opt/gowin-license/Gowin_LicenseServer_V2.1_linux
QT_QPA_PLATFORM=offscreen LD_LIBRARY_PATH=$S/bin $S/bin/license_server --help
# -s, --license <file> Specify the license file. Default is 'gowin.lic'
# -p, --port <port> Specify listening port number. Default is 10559
# -o, --out <location> Specify the log file location. Default is '.'
4. Run it as a service
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# /etc/systemd/system/gowin-license.service
[Unit]
Description=Gowin floating license server
After=network-online.target
[Service]
User=gowin
Environment=QT_QPA_PLATFORM=offscreen
Environment=LD_LIBRARY_PATH=/opt/gowin-license/Gowin_LicenseServer_V2.1_linux/bin
ExecStart=/opt/gowin-license/Gowin_LicenseServer_V2.1_linux/bin/license_server \
-s /opt/gowin-license/gowin_E_XXXXXXXXXXXX_floating.lic -p 10559 -o /opt/gowin-license/log
Restart=on-failure
[Install]
WantedBy=multi-user.target
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sudo systemctl daemon-reload && sudo systemctl enable --now gowin-license
The log confirms it:
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Server started.
Listening Port: 10559
License Count: 50
5. Point the clients at it
Gotcha #2. gw_sh reads the server address only from bin/gwlicense.ini inside each Gowin installation. Setting LM_LICENSE_FILE, as many build scripts do, has no effect.
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[license]
lic="localhost:10559"
From other machines, use the server’s hostname instead of localhost. In the IDE, Help → Manage License does the same.
Gotcha #3. Pointing lic= at the .lic file itself does not work for a floating license:
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License verification failed License mode not match.
A floating license must be served; only the server reads the file.
6. Test it properly
gw_sh --version should print its banner without a “license expires” line, and the server log should show a check-out:
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Checkin
user: alice@buildhost
total: 50, used: 0, remain: 50
A passing version check doesn’t prove device entitlement, though. Build something small for your actual part:
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set_device -name GW5AST-138C GW5AST-LV138PG484AC1/I0
add_file cnt.v
set_option -top_module cnt
run all
If impl/pnr/cnt.fs appears, the whole path works: license, device, synthesis, place-and-route and bitstream.
Troubleshooting
| Symptom | Fix |
|---|---|
symbol lookup error ... libpthread.so.0 | LD_LIBRARY_PATH includes the package lib/; use bin/ only |
License mode not match | the client points at the .lic file; point it at host:port |
The license expires in N days | the client still uses another server; check gwlicense.ini |
| Server refuses the license | the MAC changed; compare HOST_ID with /sys/class/net/<nic>/address |
| Clients can’t connect | is the port listening (ss -ltn \| grep 10559)? Is a firewall in the way? |
Lessons
- Don’t put it in a container. The license is locked to a MAC address. A Kubernetes pod gets a new random MAC every time it restarts, so the license fails. Run the server on a fixed machine and let containers connect to it over the network.
- Virtual machines need a pinned MAC. Our server runs on a KVM VM. Its MAC stays the same unless someone recreates the network card, so we wrote it into the admin notes.
- The server has no authentication. Anyone who can reach the port can take a seat. Firewall it to your own network.
- Seats are shared. We opened ours to the whole campus. That’s good for students, but a full server also blocks your own overnight runs, so ask for enough seats. When we asked, Gowin reissued our license with 50 seats instead of 10, on the same day.
- Put the renewal in your calendar. Floating licenses expire. Re-apply a month early.
Why this is worth doing for Thai universities
Gowin’s devices and boards are inexpensive, and the license for academic use is free. That makes them a realistic platform for teaching FPGA design and for research that needs real silicon, not just simulation. What’s missing is the operational know-how: one afternoon of setup that each lab tends to rediscover alone. A faculty that runs its own license server can share it across campus. It owns that piece of its toolchain instead of borrowing it.
References
[1] S. Sanghlao and S. Sanglao, “Agentic LLM-Driven RTL Design for Factor-Graph Processing Elements Using a Containerized EDA Loop,” Proc. APSIPA ASC 2026, to appear.