The Google Serial Graphics Adapter BIOS, or SGABIOS, provides a means for legacy x86 software to communicate with an attached serial console as if a video card were attached. It is designed to be inserted into a BIOS as an option ROM to provide over a serial port the display and input capabilities normally handled by a VGA adapter and a keyboard, and additionally provide hooks for logging displayed characters for later collection after an operating system boots. It is designed to handle all text mode output sent to the legacy video BIOS int 10h service routine. Int 10h is the most common method for displaying characters in 16-bit legacy x86 code.
Red Hat 8.0 omits playmidi
Red Hat 8.0 failed to include playmidi because of an issue with the HZ value varying across compatible x86 platforms (causing 6x faster playback on x86-64 for example). They never gave me a bug report but instead just silently omitted it. If playmidi is compiled with the same kernel includes as the currently executing kernel, it should not suffer from this problem. I plan to release a dynamic HZ adjustment fix in a few weeks.