linux-kernel - Re: Definition of BUG on x86

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Message-ID: <20090219164104.GA20941@elte.hu>
Date:	Thu, 19 Feb 2009 17:41:04 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Petr Tesarik <ptesarik@...e.cz>, "H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Definition of BUG on x86


* Jeremy Fitzhardinge <jeremy@...p.org> wrote:

> Ingo Molnar wrote:
>> Well, the important question is thatGCC will optimize out whatever 
>> comes after the __builtin_trap(), right? To guarantee an assert we can 
>> do something like:
>>
>>  	__builtin_trap();
>> 	panic("should never get here");
>>
>> to guarantee a message. (But realistically GCC will at most generate a 
>> build error.)
>
> Ah, right, I remember the problem.  There's no guaranteed way 
> of getting the address of the ud2a instruction __builtin_trap 
> generates to put it into the bug table.

hm, indeed.

So that 2 byte overhead will be there for now, until gcc (or 
some other compiler) is improved.

	Ingo
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