Re: Debian kernel regression, was Re: Modernizing a Macintosh LC III

[Geert Uytterhoeven <geert@linux-m68k.org>]

On Fri, Nov 22, 2013 at 12:47 AM, Finn Thain <fthain@telegraphics.com.au> wrote:
> On Thu, 21 Nov 2013, Geert Uytterhoeven wrote:
>
>> Unable to handle kernel NULL pointer dereference at virtual address   (null)
>> Oops: 00000000
>> PC: [<0013ad28>] __pmz_startup+0x32/0x2a0
>
> [snip]
>
>> Call Trace: [<002c5d3e>] pmz_console_setup+0x64/0xe4
>>  [<00009600>] atari_keyboard_interrupt+0x164/0x2dc
>>  [<000499f4>] register_console+0x104/0x2a6
>>  [<000fc4a8>] strlen+0x0/0x14
>>  [<00048b96>] printk+0x0/0x26
>>  [<002c5cd4>] pmz_console_init+0x10/0x16
>
> [snip]
>
>>
>> drivers/tty/serial/pmac_zilog.c needs some MACH_IS_MAC() tests.
>>
>
> The platform devices pmz_ports[X].pdev aren't supposed to be used unless
> config_mac() first initializes them (when MACH_IS_MAC). Unfortunately the
> null pointer test in pmz_console_setup() never succeeds because
> pmz_probe() always sets those pointers, so make sure they remain null when
> the platform device isn't valid.
>
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
>
> ---
>
> I haven't even compiled this. Geert, can you please build and test?

Worse, now it crashes without output.

Adding more debug code in printk() itself showed that pmz_console_setup()
no longer crashes, but that it dies in serial_console_write() later, hiding all
evidence.

Woops, serial_console_write() is the one from amiserial...

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