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Date: Tue, 24 Jul 2007 10:03:43 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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Subject: Re: [PATCH][RFC] getting rid of stupid loop in BUG()
References: <20070724153916.GS21668@ftp.linux.org.uk> <46A62F35.2000501@goop.org>
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To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Al Viro <viro@ftp.linux.org.uk>, Linus Torvalds <torvalds@linux-foundation.org>, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
List-ID: <linux-arch.vger.kernel.org>

Jeremy Fitzhardinge wrote:
> Al Viro wrote:
>> 	AFAICS, the patch below should do it for i386; instead of
>> using a dummy loop to tell gcc that this sucker never returns,
>> we do
>> static void __always_inline __noreturn __BUG(const char *file, int line);
>> containing the actual asm we want to insert and define BUG() as
>> __BUG(__FILE__, __LINE__).  It looks safe, but I don't claim enough
>> experience with gcc __asm__ potential nastiness, so...
>>
>> Comments, objections?
>>   
> 
> Does it work?  When I wrote the BUG code I tried this, but gcc kept
> warning about "noreturn function returns".  I couldn't work out a way to
> convince gcc that the asm is the end of the line.
> 
> I'm actually in favour of dropping the loop and the noreturn stuff
> altogether.  It means that gcc thinks everything is live at the time of
> the BUG, and the debugging info at the point of the ud2a is more useful.

How much code would that add to the kernel?

	-hpa