On Fri, 5 Feb 2021 at 22:01, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > > Userspace has discovered the functionality offered by SYS_kcmp and has > started to depend upon it. In particular, Mesa uses SYS_kcmp for > os_same_file_description() in order to identify when two fd (e.g. device > or dmabuf) As you rightfully point out, SYS_kcmp is a bit of a two edged sword. While you mention the CONFIG issue, there is also a portability aspect (mesa runs on more than just linux) and as well as sandbox filtering of the extra syscall. Last time I looked, the latter was still an issue and mesa was using SYS_kcmp to compare device node fds. A far shorter and more portable solution is possible, so let me prepare a Mesa patch. -Emil
