linux-kernel - Re: [PATCH] Put the BUG __FILE__ and __LINE_

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Message-ID: <20060928101555.GA99906@muc.de>
Date:	Thu, 28 Sep 2006 12:15:55 +0200
From:	Andi Kleen <ak@....de>
To:	Andrew Morton <akpm@...l.org>
Cc:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Put the BUG __FILE__ and __LINE__ info out of line

On Thu, Sep 28, 2006 at 12:26:10AM -0700, Andrew Morton wrote:
> On 28 Sep 2006 09:17:31 +0200
> Andi Kleen <ak@....de> wrote:
> 
> > > Plan #17 is to just put the BUG inline and then put the EIP+file*+line into
> > > a separate section, then search that section at BUG time to find the record
> > > whose EIP points back at this ud2a.
> > > 
> > > It's a bit messy for modules, but it minimises the .text impact and keeps
> > > disassembly happy, no?
> > > 
> > > And if done right it can probably be used by other architectures.
> > 
> > 
> > The way x86-64 solved it was to turn the inline code into valid
> > instructions. This can be done with two additional bytes.
> > IMHO that's the right solution for the problem on i386 too
> > 
> 
> That uses even more text.

But no out of line section. So overall it's smaller, although the cache footprint
is 2 bytes larger. But then is 2 bytes larger really an issue? We don't have
_that_ many BUGs anyways.

I'll port the x86-64 way over to i386

-Andi
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