[PATCH] loader: Use RTLD_DEEPBIND if available to prefer local symbols

[Egbert Eich]

On Wed, Aug 14, 2013 at 04:08:06PM +0200, Mark Kettenis wrote:
> 
> That's indeed a concern I have.  I think RTLD_DEEPBIND is only
> available with glibc.  So basically, this would sweep some fundamental
> design problems in Mesa under the carpet on the dominant platform,
> leaving everybody else out in the cold.
> 
> The person who added the feature thinks highly of the people who think
> they need this: it:
> 
>   <http://sourceware.org/ml/libc-hacker/2004-09/msg00083.html>

Of course I agree with you there. 
There's another side to this, though: 

We had this set at SUSE for quite some time now. 

There was a support case where a customer needed to use two drivers 
one of which had code copied from the other.
It took quite a while until we realized this and found out that one 
driver was actually using code from the other (which had divereged
and thus caused a crash).
In the end our findings were irrelevant for upstream as the code 
there had been scheduled for removal already.

If you work for a vendor who ships products with a long term support 
commitment you would like to make sure your environment is 'robust' 
to spare your customer of any avoidable disruption and yourself of 
additional support burdeon. Thus added this feature.

I went ahead and posted this patch as I thought it might be useful 
to others who are in a similar situation.
 
We could make this feature configurable - and leave off by default.


Cheers,
	Egbert.