Re: [PATCH v3 5/6] parisc: wire up rseq system call

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: firoz.khan@linaro.org
Cc: Helge Deller <deller@gmx.de>,
	Parisc List <linux-parisc@vger.kernel.org>,
	"James E.J. Bottomley" <jejb@parisc-linux.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg KH <gregkh@linuxfoundation.org>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	y2038 Mailman List <y2038@lists.linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-Arch <linux-arch@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Deepa Dinamani <deepa.kernel@gmail.com>,
	marcin.juszkiewicz@linaro.org
Subject: Re: [PATCH v3 5/6] parisc: wire up rseq system call
Date: Mon, 8 Oct 2018 10:23:33 +0200	[thread overview]
Message-ID: <CAMuHMdWOKmnn18yS_dHNjgT8rrVsUc3ipGpMTQbyEBujHuVE8w@mail.gmail.com> (raw)
In-Reply-To: <CALxhOniZQEMCOY-B1F5=MCdpCYMbeGQAJTtPXhVyJ5TxtOEA5A@mail.gmail.com>

Hi Firoz,

On Mon, Oct 8, 2018 at 8:49 AM Firoz Khan <firoz.khan@linaro.org> wrote:
> On Mon, 8 Oct 2018 at 11:36, Helge Deller <deller@gmx.de> wrote:
> > On 08.10.2018 07:52, Firoz Khan wrote:
> > > On Mon, 8 Oct 2018 at 11:11, Helge Deller <deller@gmx.de> wrote:
> > >> On 08.10.2018 07:16, Firoz Khan wrote:
> > >>> Signed-off-by: Firoz Khan <firoz.khan@linaro.org>
> > >>> ---
> > >>>  arch/parisc/kernel/syscalls/syscall.tbl | 3 ++-
> > >>>  1 file changed, 2 insertions(+), 1 deletion(-)
> > >>>
> > >>> diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
> > >>> index 4e85293..4334bb7 100644
> > >>> --- a/arch/parisc/kernel/syscalls/syscall.tbl
> > >>> +++ b/arch/parisc/kernel/syscalls/syscall.tbl
> > >>> @@ -349,4 +349,5 @@
> > >>>  347     common  preadv2                         sys_preadv2                     compat_sys_preadv2
> > >>>  348     common  pwritev2                        sys_pwritev2                    compat_sys_pwritev2
> > >>>  349     common  statx                           sys_statx
> > >>> -350  common  io_pgetevents                   sys_io_pgetevents               compat_sys_io_pgetevents
> > >>> \ No newline at end of file
> > >>> +350  common  io_pgetevents                   sys_io_pgetevents               compat_sys_io_pgetevents
> > >>> +351  common  rseq                            sys_rseq                        compat_sys_rseq
> > >>
> > >> You can't add the rseq syscall for parisc yet.
> > >> It needs additional code in the kernel for parisc which hasn't been tested yet.
> > >> See my initial untested patch at https://patchwork.kernel.org/patch/10495209/
> > >
> > > Thanks for your update!
> > >
> > > When I compiled the kernel I got below warnings.
> > >
> > > <stdin>:696:2: warning: #warning syscall nfsservctl not implemented [-Wcpp]
> > > <stdin>:1335:2: warning: #warning syscall rseq not implemented [-Wcpp]
> > >
> > > I added an IGNORE entry nfsservctl in script/checksyscalls.sh because this
> > > syscall is gone. But we definitely have to keep rseq entry on parisc
> > > architecture.
> >
> > I prefer to keep the warning for rseq for now.
>
> I'm fine with this.
>
> > It reminds me that we still may want the rseq syscall.
> > If the warning is a problem, you may simply add the __IGNORE_rseq define.
>
> But I still feel to keep an IGNORE entry, so once you test your patch; we can
> remove IGNORE entry and update the syscall.tbl.

If the warning is bogus (e.g. obsolete syscall), an IGNORE entry
should be added.
If the warning is due to a not-yet-implemented feature, IMHO it should not be
silenced, as that would give the false impression that the feature is
present and
implemented.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds