GNU Project some is released under a weak copyleft or a lax, push-over free software license. The first goal of the GNU project was to create a whole free-software operating system. By 1992, the GNU project had completed all of the major operating system utilities, but had not completed their proposed operating system kernel, GNU Hurd. With the release of the Linux kernel, started independently by Linus Torvalds in 1991, and released under the GPL with version 0.12 in 1992, for the first time it was possible to run an operating system composed completely of free software. Though the Linux kernel is
Hybrid kernel Hybrid kernel A hybrid kernel is an operating system kernel architecture that attempts to combine aspects and benefits of microkernel and monolithic kernel architectures used in computer operating systems. The traditional kernel categories are monolithic kernels and microkernels (with nanokernels and exokernels seen as more extreme versions of microkernels). The "hybrid" category is controversial, due to the similarity of hybrid kernels and ordinary monolithic kernels; the term has been dismissed by Linus Torvalds as simple marketing. The idea behind a hybrid kernel is to have a kernel structure similar to that of a microkernel, but to implement that structure in