You missed the next paragraph, in which it says that as they looked further into it, they discovered Linux kernel violations as well. LWN has some more detaile

You missed the next paragraph, in which it says that as they looked further into it, they discovered Linux kernel violations as well. LWN has some more detailed coverage, describing the proprietary vmkernel component that gets loaded into the kernel as a kernel module, and the specific files from the kernel that are included in this: http://lwn.net/SubscriberLink/635290/d7304b50a2ef15b0/ http://lwn.net/SubscriberLink/635290/d7304b50a2ef15b0/ This is much deeper than simply a binary kernel module that uses the exported interfaces; it also appears to copy wholesale large parts of kernel internals, not just access the kernel via defined interfaces.