Subject: Re: [PATCH][RE-SUBMIT] Default setting of the ARM_UNWIND option
From: Catalin Marinas <catalin.marinas@arm.com>
To: Claudio Scordino <claudio@evidence.eu.com>
Cc: linux-kernel@vger.kernel.org, rmk+kernel@arm.linux.org.uk,
       linux-arm-kernel@lists.arm.linux.org.uk, akpm@linux-foundation.org
In-Reply-To: <4AE55D83.7080608@evidence.eu.com>
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	 <4AE55D83.7080608@evidence.eu.com>
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Organization: ARM Ltd
Date: Mon, 26 Oct 2009 11:10:52 +0000
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On Mon, 2009-10-26 at 09:27 +0100, Claudio Scordino wrote:
> My ARM board hanged at the initial "Calibrating delay loop" message.
> 
> After some inspection, I found out the problem to be with commit
> adf8b37bafc1495393201a2ae4235846371870d0. This commit introduces stack
> unwinding for ARM, and set it enabled by default. However, it seems to
> not work with buggy or not-EABI compilers.
> 
> My suggestion is to keep the feature (which is fine) but change the
> default setting of the option (see the attached patch).

The option still depends on EXPERIMENTAL, so you get ARM_UNWIND on when
enabling that.

I'm more in favour of a #warning on #error in the unwind.c file based on
the compiler version rather than not having it on by default. The reason
is that people reported performance improvements when compiling the
kernel without frame pointers.

-- 
Catalin

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