So, you’re wondering, what exactly is the tuxcall unsupported
syscalls in Linux? It was actually that Red Hat implemented a web
server in-kernel to beat Microsoft in a contest! Later, when Linux
improved its threading support by adding NPTL, and also adding the
sendfile system call, this virtually closed the entire gap between
the in-kernel web server and a userspace one.
20190629/DuckDuckGo tux api
20190629/DuckDuckGo tux syscall
https://cloudatomiclab.com/antisyscall
20190629/DuckDuckGo tuxcall
20190629/https://unix.stackexchange.com/questions/446502/what-did-the-system-call-tuxcall-do
20190629/https://en.wikipedia.org/wiki/NPTL