# Kernels ## Available OpenCL kernels See directory `kernel`. ## Parameter configuration ### Common In general, switching kernels requires reconfiguring mining parameters, such as (but not necessarily limited to) `thread-concurrency`, `intensity`, `gpu-engine` and `gpu-memclock`. A description of how to do this is available in `doc/MINING`. ### alexkarnew Alexey Karimov's optimised kernel, based on `ckolivas`. For Catalyst >=13.4. Only supports `vectors=1`. [Announcement](https://litecointalk.org/index.php?topic=4082.0). ### alexkarold Alexey Karimov's optimised kernel, based on `ckolivas`. For Catalyst <13.4. Only supports `vectors=1`. [Announcement](https://litecointalk.org/index.php?topic=4082.0). ### ckolivas The original Colin Percival `scrypt` kernel, maintained for a long time by Con Kolivas in `cgminer` and renamed to reflect the fact. Only supports `vectors=1`. ### psw Pavel Semjanov optimised kernel, SHA256 speedups. [Announcement](https://bitcointalk.org/index.php?topic=369858.0). ### zuikkis Zuikkis' optimised kernel, based on `ckolivas`. Only supports `vectors=1`, `lookup-gap=2` and `worksize=256`. [Announcement](https://litecointalk.org/index.php?topic=6058.msg90873#msg90873). ## Submitting new kernels ### Requirements * OpenCL source code only, licenced under GPLv3 (or later). * Not hard-coded for a specific GPU model or manufacturer. * Known limitations and any specific configuration quirks must be mentioned. ### Procedure 1. Copy the kernel you wish to modify, change the file encoding to UTF-8 and commit it without any further modifications. This way, it is easy to verify that there are no hidden changes. Note in the commit message which kernel is used as a base. 2. Make changes to the kernel. Commit them. This allows to produce a diff that makes sense. 3. Search for KL_CKOLIVAS and CKOLIVAS_KERNNAME in the top-level source directory and make additions to the listed files in order to integrate the new kernel. Now it can be selected when starting via the `--kernel` argument or `kernel` configuration option. 4. Recompile and test that the kernel actually works. 5. Add yourself to the "kernels" section in `AUTHORS.md`. Keep it short. 6. Submit a pull request on GitHub, or file it at the issue tracker, outlining the changes made, known limitations, and tested GPUs. List your git repository and branch name. The current repository and issue tracker links should be in `README.md`.