On Thu, Nov 8, 2018 at 3:36 PM, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: [...] > Changes in v8: > - Rebased onto 65102238 (4.20-rc1). > - Added a note to the cover letter on why syscall wrappers/shims that untag > user pointers won't work. > - Added a note to the cover letter that this patchset has been merged into > the Pixel 2 kernel tree. > - Documentation fixes, in particular added a list of syscalls that don't > support tagged user pointers. Hi Catalin, I've changed the documentation to be more specific, please take a look. I haven't done anything about adding a way for the user to find out that the kernel supports this ABI extension. I don't know what would the the preferred way to do this, and we haven't received any comments on that from anybody else. Probing "on some innocuous syscall currently returning -EFAULT on tagged pointer arguments" works though, as you mentioned. As mentioned in the cover letter, this patchset has been merged into the Pixel 2 kernel tree. Thanks!