Linux Vserver wasn't/isn't kernel modules, but a patchset that directly modifies the kernel. It works based on so-called contexts; a process in a context cannot

Linux Vserver wasn't/isn't kernel modules, but a patchset that directly modifies the kernel. It works based on so-called contexts; a process in a context cannot see processes in other contexts (at all), with the exception of context 0 which is the "root context", or if you disable PID isolation. VServer was a competing implementation to what evolved into LXC, as such it implemented similar concepts, such as PID namespacing, pretty early, using own code. It's just the looks though. VS used a single global namespace, but individual guest contexts could not "see" PIDs outside of their context. See https://www.kernel.org/doc/ols/2007/ols2007v2-pages-151-160.pdf https://www.kernel.org/doc/ols/2007/ols2007v2-pages-151-160....