Making of Hyperthreads
I have been working on a fun project where I am trying to virtualize a MIPS machine. For a QEMU emulated NE2000 based network device and for couple of system daemons, I needed a light threaded framework. While the earlier design was that anything in hypervisor context was run on CPU and thus was completely serialized. So we decided on doing something differently here. We created a virtual CPU and named it hypercore. This virtual CPU is supposed to run anything in context of hypervisor. This virtual CPU, whenever scheduled, always works in kernel mode. The idea was simple, anything of _maintenance_ sort was scheduled later on that hypercore. I then went on implementing the threading mechanism. Its very similar to what is know as kernel threads in Linux(R) world. There is one function which the thread is supposed to execute. Threads have a lifetime: they are created, run, paused, run again and then finally destroyed. Initial implementation was non-preemtible. This means that threa...