#libucontext is a new implementation of the ucontext C APIs (makecontext, swapcontext, etc) for musl-based distributions such as #alpinelinux. right now it only supports x86_64 and static linking but it hasn't been released yet :)
http://github.com/kaniini/libucontext
we intend to use it with the gcompat package to provide the stubbed ucontext symbols presently there