What is Virtual Context Separation?
Virtual Context Separation is a separation inside the Linux kernel, that gives you the posibility to run several separate userland context's ontop of the same kernel. The separation happens in the kernel.
Those userland contexts are mostly independent. They can not see each others processes, they can not see each other and will not interfere with eachother in any way.
Resources, Flags and Capabilities are per Context. This allows you to limit the userland context in various ways. Like memory, cpu time, network IO, disk access.