linux-kernel - Re: [PATCH 0/3] System call table generation support

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Message-ID: <20180917171720.wda5qrl7hyyacmwl@pburton-laptop>
Date:   Mon, 17 Sep 2018 17:17:23 +0000
From:   Paul Burton <paul.burton@...s.com>
To:     Firoz Khan <firoz.khan@...aro.org>
CC:     Hauke Mehrtens <hauke@...ke-m.de>,
        Rafał Miłecki <zajec5@...il.com>,
        "linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        James Hogan <jhogan@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        "y2038@...ts.linaro.org" <y2038@...ts.linaro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "deepa.kernel@...il.com" <deepa.kernel@...il.com>,
        "marcin.juszkiewicz@...aro.org" <marcin.juszkiewicz@...aro.org>
Subject: Re: [PATCH 0/3] System call table generation support

Hi Firoz,

On Fri, Sep 14, 2018 at 02:08:31PM +0530, Firoz Khan wrote:
> The purpose of this patch series is:
> 1. We can easily add/modify/delete system call by changing entry 
> in syscall.tbl file. No need to manually edit many files.
> 
> 2. It is easy to unify the system call implementation across all 
> the architectures. 
> 
> The system call tables are in different format in all architecture 
> and it will be difficult to manually add or modify the system calls
> in the respective files manually. To make it easy by keeping a script 
> and which'll generate the header file and syscall table file so this 
> change will unify them across all architectures.

Interesting :)

I actually started on something similar recently with the goals of
reducing the need to adjust both asm/unistd.h & the syscall entry tables
when adding syscalls, clean up asm/unistd.h a bit & make it
easier/cleaner to add support for nanoMIPS & the P32 ABI.

My branch still needed some work but it's here if you're interested:

    git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux.git wip-mips-syscalls

    https://git.kernel.org/pub/scm/linux/kernel/git/mips/linux.git/log/?h=wip-mips-syscalls

There are some differences:

  - I'd placed syscall numbers the 3 current MIPS ABIs in one table,
    rather than splitting it up. I can see pros & cons to both though so
    I'm not tied to having a single all-encompassing table.

  - I'd mostly inferred the entry point names from the syscall names,
    only specifying them where they differ. Again I'm not particularly
    tied to this.

  - I'd made asm/unistd.h behave like asm-generic/unistd.h with the
    __SYSCALL() macro, where you generate separate syscall_table_*
    headers. I'm fine with that too.

So I'm pretty happy to go with your series, though I agree with Arnd on
the ABI/file naming & the missing syscalls that were added in the 4.18
cycle. We probably need to provide mipsmt_sys_sched_[gs]etaffinity as
aliases to sys_sched_[gs]etaffinity when CONFIG_MIPS_MT_FPAFF isn't
enabled in order to fix the issue the kbuild test robot reported.

But I'm looking forward to v2 :)

Thanks,
    Paul