On 10/31/2016 05:08 PM, Mark Rutland wrote: > When an architecture does not select CONFIG_ARCH_HAS_PKEYS, the pkey_alloc > syscall will return -ENOSPC for all (otherwise well-formed) requests, as the > generic implementation of mm_pkey_alloc() returns -1. The other pkey syscalls > perform some work before always failing, in a similar fashion. > > This implies the absence of keys, but otherwise functional pkey support. This > is odd, since the architecture provides no such support. Instead, it would be > preferable to indicate that the syscall is not implemented, since this is > effectively the case.
This makes the behavior of an x86 cpu without pkeys and an arm cpu without pkeys differ. Is that what we want? An application that _wants_ to use protection keys but can't needs to handle -ENOSPC anyway. On an architecture that will never support pkeys, it makes sense to do -ENOSYS, but that's not the case for arm, right?
