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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Tue, 25 Sep 2018 08:00:28 +0200
Message-ID: <CAK8P3a2=kxoum6hcPR2UN_St2PaFtZud_NNVkK9rHaf=N7ym-g@mail.gmail.com>
Subject: Re: [PATCH 2/3] powerpc: Add system call table generation support
To:     Michael Ellerman <mpe@ellerman.id.au>
Cc:     Firoz Khan <firoz.khan@linaro.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>, linuxram@us.ibm.com,
        leitao@debian.org, Boqun Feng <boqun.feng@gmail.com>,
        gregkh <gregkh@linuxfoundation.org>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        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>,
        Deepa Dinamani <deepa.kernel@gmail.com>,
        Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
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On Tue, Sep 25, 2018 at 2:48 AM Michael Ellerman <mpe@ellerman.id.au> wrote:
> Arnd Bergmann <arnd@arndb.de> writes:
> > On Tue, Sep 18, 2018 at 2:15 PM Firoz Khan <firoz.khan@linaro.org> wrote:
> >> On 14 September 2018 at 15:31, Arnd Bergmann <arnd@arndb.de> wrote:
> >> > On Fri, Sep 14, 2018 at 10:33 AM Firoz Khan <firoz.khan@linaro.org> wrote:
> >
> > But all three existing architectures (x86, s390 and arm) already
> > have the capability to parse the table and generate different output
> > from that.
>
> Yeah, we want that on powerpc too.
>
> If the script needs to be more complex that's fine, if it can't be
> shared across arches that's fine, the main thing for me is that wiring
> up a syscall can be done by adding a single line in a single file.

Yes, that's definitely the idea, we want to make it easier for everyone.
We need at least a special case for mips, which needs three separate
input files (the tables are completely different) to generate four versions
of the output, plus a future extension to use the generic table for their
new one.

For powerpc, I'm hoping that both the table format and script can be
completely generic and not need a special case that is different
from the others, but if we need some extra magic to handle the SPU
syscalls, we can still do that with a private script.

      Arnd