Re: [PATCH 15/15] arch: add pkey and rseq syscall numbers everywhere

[Arnd Bergmann]

On Tue, Jan 15, 2019 at 12:52 PM Russell King - ARM Linux admin
<linux@xxxxxxxxxxxxxxx> wrote:
>
> On Thu, Jan 10, 2019 at 05:24:35PM +0100, Arnd Bergmann wrote:
> > 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