On Mon, Nov 05, 2018 at 09:39:29PM +0200, Nick Kossifidis wrote: > a) By directly modifying your custom CSRs, it means that we will need > compiler support in order to compile a kernel with your code in it. This > will break CI systems and will introduce various issues on testing and > reviewing your code. In general if we need custom toolchains to compile > the kernel, that may be unavailable (vendors will not always open source > their compiler support), we won't be able to maintain a decent level of > code quality in the tree. How can the maintainer push your code on the > repository if he/she can't even perform a basic compilation test ?
And that (besides avoiding the wild growth of extensions) is the major reason why accepting vendor specific CSRs or instructions is a no-go.