Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) client-ip=2620:137:e000::3:3;
Subject: Re: arch/m68k/include/asm/raw_io.h:91:13: warning: array subscript 0
 is outside array bounds of 'volatile u16[0]' {aka 'volatile short unsigned
 int[]'}
To:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Rob Herring <robh@kernel.org>
Cc:     kernel test robot <lkp@intel.com>, oe-kbuild-all@lists.linux.dev,
        linux-kernel@vger.kernel.org,
        Wim Van Sebroeck <wim@linux-watchdog.org>
References: <202309192013.vI4DKHmw-lkp@intel.com>
 <CAL_JsqJ0BoR7Dan3=oyWPa6HU3YV=eOFTO5fx7u5zz2i=eB-jQ@mail.gmail.com>
 <a57afd40-71a2-aa68-84cb-44d2a88a1e2b@roeck-us.net>
 <CAL_JsqJYPJVTxH=d5nYK78+ZWhZAfh4VhEyBLqzyg4MzMhrX0g@mail.gmail.com>
 <194e2d22-9eff-ec6c-9bc9-13b62bda870a@roeck-us.net>
 <CAL_JsqKcD4AttSVUEi5zuF8S1E4xNdqdZVKiHmk0r79SRW5Cqw@mail.gmail.com>
 <ad1f36ab-29a6-98b6-8782-3980323760e1@roeck-us.net>
 <CAMuHMdXsiSfp3DGnLXfuENVLOdG91a+GXj3+g9p8Yp6aGTuqDQ@mail.gmail.com>
From:   Michael Schmitz <schmitzmic@gmail.com>
Message-ID: <fe7e6c19-916e-a30b-6f59-df03812fa431@gmail.com>
Date:   Fri, 22 Sep 2023 13:53:13 +1200
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:78.0)
 Gecko/20100101 Thunderbird/78.14.0
MIME-Version: 1.0
In-Reply-To: <CAMuHMdXsiSfp3DGnLXfuENVLOdG91a+GXj3+g9p8Yp6aGTuqDQ@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hi Geert,

Am 21.09.23 um 19:08 schrieb Geert Uytterhoeven:
> Hi Günter, Rob,
>
> CC Michael
>
> On Wed, Sep 20, 2023 at 11:09 PM Guenter Roeck <linux@roeck-us.net> wrote:
>> On 9/20/23 09:20, Rob Herring wrote:
>> [....]
>>
>>>> Sure, but I still argue that this isn't worth it for drivers like this one.
>>>> Are you going to submit a fix ? Because otherwise I'll submit a patch
>>>> to drop COMPILE_TEST from MACHZ_WDT.
> I think dropping COMPILE_TEST from MACHZ_WDT is the right thing to do
> anyway.  Unlike most other drivers, this is not a driver that can be
> compiled in, and doesn't do anything if the hardware is not present.
> In fact it is a very dangerous driver: its probe function "reads" the
> ZF version register, but that involves doing an unconditional write,
> which might crash any non-X86 system.
>
> IMHO a driver must not be enabled for compile-testing if its presence
> can harm the system.
>
>>> I honestly don't know what the fix is. There's a compiler flag to
>>> allow 0 address, but that seems like a big hammer. From what I read on
>>> the fix for gcc-12, we shouldn't be getting this, but I haven't
>>> confirmed. I was hoping for comment from Geert as the issue doesn't
>>> appear to be the driver, but the arch code.
> Well, Atari ROM port ISA accesses are really weird, due to the really
> weird way the bus is wired to the address/data lines...

Putting it mildly ...

> The issue is that gcc considers accessing these addresses as "not
> done"...
That an new GCC problem?
>>> Furthermore, I just built the same HEAD and config as reported and
>>> don't see this error. I'm using kernel.org nolibc gcc 13.2.0 which
>>> should be the same version.
>> Exactly my point. So now we are stuck with a report like this on a
>> driver which probably has 0 users and we don't know how to fix it,
>> all to get the benefit of being able to compile it for an architecture
>> and platform which will never use it.
>>
>> I seem to recall similar errors with m68k and COMPILE_TEST last time
>> I tried to enable it on watchdog drivers, so I am not sure if this is
>> entirely new.
> Probably not.
>
> Michael: original build failure report in
> https://lore.kernel.org/r/202309192013.vI4DKHmw-lkp@intel.com/

From what I can see, DATA_W appears to be zero - maybe the driver needs
to set 'sane' values for IO ports if compile tested on non-ISA
architectures?

In the alternative, we might have to prevent setting ATARI_ROM_ISA if
COMPILE_TEST is set.

Cheers,

    Michael


>
> Gr{oetje,eeting}s,
>
>                         Geert
>