linux-kernel - Re: [RFC/PATCH-mm] i8042: activate panic blink only in X

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Date:	Tue, 05 Sep 2006 10:16:45 +1000
From:	Grant Coady <gcoady.lk@...il.com>
To:	Andreas Mohr <andi@...x01.fht-esslingen.de>
Cc:	Andi Kleen <ak@...e.de>, Dmitry Torokhov <dtor@...ightbb.com>,
	Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC/PATCH-mm] i8042: activate panic blink only in X

On Tue, 5 Sep 2006 01:03:58 +0200, Andreas Mohr <andi@...x01.fht-esslingen.de> wrote:

>Hi,
>
>On Tue, Sep 05, 2006 at 08:29:09AM +1000, Grant Coady wrote:
>> If possible, kill the console blank timer too?  (dunno if you have).
>> 
>> Example: Oops screen on 2.4 recently I paged up to where the fault 
>> started, the screen blanker kicked in while I was hand copying info 
>> and wiped previous screens :(  Caused significant delay in working 
>> out what the issue was (slackware-10.2 2.4.33.1 glibc nptl boo-boo).
>> 
>> Is it safe / easy to do on oops/panic?
>
>It should be as easy as e.g. doing a
>
>int system_oopsed __read_mostly = 0;

Can't see where to set this one, from the kernel/panic.c notifier chain?

>if (!system_oopsed)
>    blank();

drivers/char/vt.c:
...
static void blank_screen_t(unsigned long dummy)
{
        if (unlikely(!keventd_up())) {
                mod_timer(&console_timer, jiffies + blankinterval);
                return;
        }
        blank_timer_expired = 1;
        schedule_work(&console_work);
}

Looks like the place to stop the screen blanker, that's as far as I'm game 
to travel.  

Hooking the panic notifier chain looks too scary for this little black duck ;)

Grant.
>
>in the timer handler as opposed to painfully deregistering the whole handler
>in the critical system state after an OOPS.
>A funny side effect is that this way even improves system stability
>after OOPS, since the blanking (which doesn't happen then)
>might bomb, too ;)
>
>Andreas Mohr

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