SDL2 Upstreams OS/2 Support
While OS/2 is no longer maintained by IBM and was never really a gaming platform for where SDL2 is most commonly used, this software library that serves as an abstraction layer for multimedia/gaming hardware components and software platforms has merged the OS/2 port.
SDL2 supports all major platforms given how widely used the software is especially among cross-platform games but rather peculiar seeing OS/2 support finally mainlined in 2020. There has been out-of-tree SDl2 for OS/2 including support for the off-shoots ArcaOS and eComStation. Back in the day SDL 1.2 supported OS/2 but support was removed from SDL 2.0.
The OS/2 port was today upstreamed into the Mercurial development repository.
Known shortcomings in the SDL2 OS/2 port include the lack of OpenGL, joystick, and audio capture interfaces. Using the OS/4 kernel and patching VMAN and DIVE libraries are known to enhance the video output performance.
The eComStation variant of OS/2 appears to still be offered to commercial customers although their public website is extremely limited. ArcaOS as the other prominent OS/2 based closed-source operating system is seeing new releases and just this year picked up USB 3.0 support and other updates.