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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Jakub Bogusz <qboosh@pld-linux.org>
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Date: Wed, 15 Jun 2005 09:11:29 +1000
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Cc: Andrew Morton <akpm@osdl.org>, linuxppc-dev@ozlabs.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2.6][PPC32] RESEND: don't recursively crash in die() on
	CHRP/PReP machines
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On Tue, 2005-06-14 at 21:38 +0200, Jakub Bogusz wrote:
> This patch avoids recursive crash (leading to kernel stack overflow) in
> die() on CHRP/PReP machines when CONFIG_PMAC_BACKLIGHT=y.
> set_backlight_* functions are placed in pmac section, which is discarded
> when _machine != _MACH_Pmac.
> 
> I already posted this patch to LKML few months ago:
> http://www.ussg.iu.edu/hypermail/linux/kernel/0412.0/0300.html
> and it has been applied to linux-2.4 tree, but still not 2.6.
> (patch was made against 2.4.27, but still applies cleanly against
> kernels up to 2.6.11.12)
> 
> Signed-off-by: Jakub Bogusz <qboosh@pld-linux.org>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

> --- linux-2.4.27/arch/ppc/kernel/traps.c.orig	Wed Apr 14 15:05:27 2004
> +++ linux-2.4.27/arch/ppc/kernel/traps.c	Mon Nov 29 19:05:28 2004
> @@ -88,8 +88,10 @@
>  	console_verbose();
>  	spin_lock_irq(&die_lock);
>  #ifdef CONFIG_PMAC_BACKLIGHT
> -	set_backlight_enable(1);
> -	set_backlight_level(BACKLIGHT_MAX);
> +	if (_machine == _MACH_Pmac) {
> +		set_backlight_enable(1);
> +		set_backlight_level(BACKLIGHT_MAX);
> +	}
>  #endif
>  	printk("Oops: %s, sig: %ld\n", str, err);
>  	show_regs(fp);
> 
>