# Suppress "System is unknown to cmake" warning

**URL:** https://discourse.cmake.org/t/suppress-system-is-unknown-to-cmake-warning/10656
**Category:** Usage
**Created:** [April 15, 2024, 9:07am UTC](https://discourse.cmake.org/t/suppress-system-is-unknown-to-cmake-warning/10656 "2024-04-15T09:07:05Z")
**Posts on this page:** 4
**Page:** 1

<div class="post-metadata">

### Author: ![erinnl](https://discourse.cmake.org/user_avatar/discourse.cmake.org/erinnl/32/2357_2.png) [@erinnl](https://discourse.cmake.org/u/erinnl)
#### Post date: [April 15, 2024, 9:07am UTC](https://discourse.cmake.org/t/suppress-system-is-unknown-to-cmake-warning/10656/1 "2024-04-15T09:07:05Z")

</div>

I wrote a toolchain file for a proprietary platform covered by NDAs.  
I was looking for a way to suppress the following warning that I can embed in the toolchain file itself.

```auto
This warning is for project developers. Use -Wno-dev to suppress it.

System is unknown to cmake, create:
Platform/REDACTED to use this system, please post your config file on discourse.cmake.org so it can be added to cmake

```

---

<div class="post-metadata">

### Author: ![ben.boeckel](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [April 27, 2024, 3:25pm UTC](https://discourse.cmake.org/t/suppress-system-is-unknown-to-cmake-warning/10656/2 "2024-04-27T15:25:03Z")

</div>

I believe you’ll need to provide a suitable `Platform/Foo.cmake` module as well. You might be able to use the `Generic` platform as an alternative?

---

<div class="post-metadata">

### Author: ![erinnl](https://discourse.cmake.org/user_avatar/discourse.cmake.org/erinnl/32/2357_2.png) [@erinnl](https://discourse.cmake.org/u/erinnl)
#### Post date: [April 29, 2024, 12:28pm UTC](https://discourse.cmake.org/t/suppress-system-is-unknown-to-cmake-warning/10656/3 "2024-04-29T12:28:24Z")

</div>

I cannot use `Generic` as there are many of these platforms.

Is there any documentation of what should go into the platform module besides the system name? Pointer sizes?

---

<div class="post-metadata">

### Author: ![ben.boeckel](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [May 18, 2024, 12:53pm UTC](https://discourse.cmake.org/t/suppress-system-is-unknown-to-cmake-warning/10656/4 "2024-05-18T12:53:30Z")

</div>

I’d look at CMake’s shipped platform files and try to follow what they do. Documentation is lacking, but adding some based on your experiences doing so would be welcome.