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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 8 May 2018 09:07:27 +0200
Message-ID: <CAMuHMdUAWfmiaZG7snEQRL1N-w69NuSYzeoQgQosQRf_JTZ5OQ@mail.gmail.com>
Subject: Re: [PATCH] nubus: Unconditionally register bus type
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Michael Schmitz <schmitzmic@gmail.com>,
        Finn Thain <fthain@telegraphics.com.au>,
        "Linux/m68k" <linux-m68k@lists.linux-m68k.org>,
        Linux Kernel Development <linux-kernel@vger.kernel.org>
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Hi Greg,

On Tue, May 8, 2018 at 9:00 AM, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> On Mon, May 07, 2018 at 09:51:12AM +1200, Michael Schmitz wrote:
>> the BUG() was triggered by loading a Mac Nubus network card module on
>> a multiplatform kernel running on an Amiga machine. Up to Finn's Nubus
>> core rewrite (this February), we've seen no errors. Since then, Nubus
>> drivers fail to register because the Nubus bus is only registered on
>> Macs.
>>
>> Can't see link order involved here at all.
>
> The link order is totally involved here :)
>
> Link order determines the order in which init calls are run, so you need
> to ensure that your bus code comes before any drivers that use that bus
> code in link order.  That way, at init time, your bus is created first,
> preventing this type of error to happen.

The issue here is not due to link ordering, but due to the bus not being
registered on a system that doesn't have that particular bus.

Akin to booting a kernel on an old PC without PCI, and loading a driver
module for a PCI network card. I guess that doesn't crash (because no one
has a PC without PCI anymore? ;-)

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