[1] He has worked as a computer programmer on the Linux kernel and on the development of the cryptographic currency mining software CGMiner.
[2] His Linux contributions include patches for the kernel to improve its desktop performance, particularly reducing I/O impact.
[7] Many of his experimental "-CK" patches, such as his prefetching and scheduling code, did not get merged with the official Linux kernel.
Discussing his reasons in an interview, he expressed frustration with aspects of the mainline kernel development process, which he felt did not give sufficient priority to desktop interactivity, in addition to hacking taking a toll on his health, work and family.
On 13 July 2011, Kolivas introduced a new piece of software for "windows, linux, OSX and other" called CGMiner, which is used for mining cryptocurrencies such as bitcoin and Litecoin.