On Tue, Jan 15, 2019 at 12:52 PM Russell King - ARM Linux admin
[off-list ref] wrote:

On Thu, Jan 10, 2019 at 05:24:35PM +0100, Arnd Bergmann wrote:

quoted

Most architectures define system call numbers for the rseq and pkey system
calls, even when they don't support the features, and perhaps never will.

Only a few architectures are missing these, so just define them anyway
for consistency. If we decide to add them later to one of these, the
system call numbers won't get out of sync then.

I was lambasted for adding the pkey syscalls for 32-bit ARM in 2016,
which will probably never support it.  Why has the attitude towards
this kind of thing now apparently become acceptable?

I was (and still am) a bit unsure about this one. A number of architectures
added the numbers that won't ever support them, but I wasn't sure if
any of those that didn't add them might need it later.

I tried to just go by the rule that anything that we list in
asm-generic/unistd.h
is probably important enough that we want to list it everywhere, even if
that includes a couple that we end up being rather architecture specific.

I'm happy to drop this patch if you or others feel that we're better off
without it though.

      Arnd