Criticism of Linux rise in prominence of operating system-level virtualization using Linux has raised the profile of attacks against the kernel, and that Linus Torvalds is reticent to add mitigations against kernel-level attacks in official releases. Linux 4.12, released in 2017, enabled KASLR by default, but its effectiveness is debated. Con Kolivas, a former kernel developer, tried to optimize the kernel scheduler for interactive desktop use. He finally dropped the support for his patches due to the lack of appreciation for his development. In the 2007 interview "Why I quit: kernel developer Con Kolivas" he stated: At LinuxCon 2009, Linux creator Linus Torvalds
Darwin (operating system) and the free/open source community benefited from being given complete control over its own operating system, which could then be used in free software distributions such as GNU-Darwin. On July 25, 2006, the OpenDarwin team announced that the project was shutting down, as they felt OpenDarwin had "become a mere hosting facility for Mac OS X related projects", and that the efforts to create a standalone Darwin operating system had failed. They also state: "Availability of sources, interaction with Apple representatives, difficulty building and tracking sources, and a lack of interest from the community have all contributed to this." The