[Xorg] Xinerama backward compatibility issues

Jay Cotton Jay.Cotton at Sun.COM
Wed Feb 18 10:42:21 PST 2004

Hi Guys:

I am a bit confused here.  Did we not have a public review for
1.5 years.  I don't recall a single comment.  We did have 2
bugs posted.

Please note that I do want a discussion on this issue, I just
wonder if we need to 'do a better' job of public review.

Yes the code is changed, it's supposed to be set up to support
window managers better.

We intended to remove 'panoramiXXX' and put in XineramaXXXX in
it place, so some of the API changes.  I guess a compatibility
layer in the API would quite the client side issues.... Just a


Egbert Eich wrote:
> I've revied the new Xinerama code on Xorg for backward
> compatibility issues with existing (and shipped) versions
> of Xinerama.
> Here are my findings:
> 1. The old PanoramiX C Bindings form libXinerama are gone. 
> 2. The Xinerama 1.1 functions that were replaced by new ones
>    are now deprecated (#ifndef XNOXINERAMABC) but still available
>    and declared in the header.
> 3. XineramaSetCenterHint(), XineramaGetCenterHint(): new functions
>    declared in the header but I couldn't find an implementation.
> 4. No backward compatibility on the wire protocol level. It least 
>    I didn't find any.
> To me 1. looks like a minor issue. libXinerama has not been built
>  dynamically so no client should require these symbols as they 
> haven't been advertised in any header (except for XPanoramiXAllocInfo() 
> which is declared in panoramiXext.h). 
> On the API/ABI level all required functions from Xinerama 1.1 seem 
> to exist except for the ones mentioned in 1.
> Unfortunately this will not help us as libXinerama has always been 
> as static library so far.
> More dramatically backward compatibility on the wire protocol level
> exists neither on the client nor on the server side. This means an 
> older client won't work on the Xorg server and a client built with 
> the new version of libXinerama will fail on older servers.
> This may create a compatibility problem.
> Egbert.
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	 Jay Cotton 		     Jay.Cotton at sun.com
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	 Sun Microsystems Inc.
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	 Sun Microsystems Inc. - X11 Server Group
          User Experience Engineering

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