# Platform RDOS

**URL:** https://discourse.cmake.org/t/platform-rdos/15506
**Category:** Development
**Created:** [February 10, 2026, 3:53pm UTC](https://discourse.cmake.org/t/platform-rdos/15506 "2026-02-10T15:53:08Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![rdos](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/r/3ec8ea/32.png) [@rdos](https://discourse.cmake.org/u/rdos)
#### Post date: [February 10, 2026, 3:53pm UTC](https://discourse.cmake.org/t/platform-rdos/15506/1 "2026-02-10T15:53:09Z")

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I need a new target OS for the OpenWatcom compiler. The compiler id configuration file contains this code:

```auto
#elif defined( __WATCOMC__ )
# if defined( __LINUX__ )
# define PLATFORM_ID "Linux"

# elif defined( __DOS__ )
# define PLATFORM_ID "DOS"

# elif defined( __OS2__ )
# define PLATFORM_ID "OS2"

# elif defined( __WINDOWS__ )
# define PLATFORM_ID "Windows3x"

# elif defined( __VXWORKS__ )
# define PLATFORM_ID "VxWorks"

# else /* unknown platform */
# define PLATFORM_ID
# endif

```

Here the following should be added:

```auto

# elif defined( __RDOS__ )
# define PLATFORM_ID "RDOS"

```

Possibly other changes are needed as well to support target RDOS. OpenWatcom has supported target RDOS for many years, so it is strange that this target is not included.

---

<div class="post-metadata">

### Author: ![brad.king](https://discourse.cmake.org/user_avatar/discourse.cmake.org/brad.king/32/11_2.png) [@brad.king](https://discourse.cmake.org/u/brad.king)
#### Post date: [February 10, 2026, 3:57pm UTC](https://discourse.cmake.org/t/platform-rdos/15506/2 "2026-02-10T15:57:06Z")

</div>

@rdos thanks. AFAIK the only reason this isn’t already supported is that no one has contributed it. Please see [CONTRIBUTING.rst](https://gitlab.kitware.com/cmake/cmake/blob/master/CONTRIBUTING.rst). If the changes involve more than pattern following and some design decisions are needed, please open an issue to discuss them.