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The Avalon story becomes clearer, but it's still murky

ChrisAnderson and Joe Bedahave posted some good Q&A about Avalon on XP. Wesner has chimedin with his opinion on the “why Longhorn” question. Moreinformation is good.

My biggest concern right now is the future of the Longhorn Driver Display Model(the LDDM). These are the kernel-mode changes to the Windows driver stack thatallow Avalon to exist in all its glory on Longhorn. It’s also the biggestchunk of Avalon that cannot be easily deployed on downlevel operating systems.Avalon-on-XP pretty much means Avalon-sans-LDDM. Having to support both theLDDM and the XPDM seems like a scope increase for the Avalon team, whichis why I’m afraid that the LDDM is going to face significant cuts inorder to make the 2006 ship date.

And this is why I’m a bit confused. Either the Avalon team is actuallyahead of schedule (meaning they have time on their hands to make existing codeplay well with the XPDM) or various Longhorn-specific features will have to becut in order meet the larger goal of shipping a downlevel-compliant frameworkby 2006. If the latter is actually the case, it seems like the LDDM and itsdependencies (the desktop compositing engine) would be good candidates for theaxe because they don’t advance the larger goal of downlevelcompatibility. If there are other Longhorn-specific features that will be cutin favor of the LDDM, I’m curious as to what those features are since Idon’t think we’ve heard of them yet…

Strategically, cutting the LDDM doesn’t make a lot of sense because itkills one of the core differentiators for Longhorn. However, it seems a viablecandidate for removal if the goal is shipping a downlevel-compatible version ofAvalon by 2006.

Can anyone out there give us some straight dope on the future of the LDDM?

 

#1 Joe Beda on 8.31.2004 at 9:24 AM

The LDDM is being driven from the DX team who are still tied to the LH train.The DWM is being delivered out of the Avalon team.While it is true that we will have to take on more work to support Avalon on XP and W2k3, it should be incremental dev work to do so.Everything we've shipped and shown has been running on the XPDM so far.The LDDM has still been in development (including new drivers -- not a trivial thing) and so Avalon works just fine on the XPDM.Things get more complicated when you have multiple Avalon apps running at the same time on the XPDM.The real question is how far we can push our hardware acceleration story on the XPDM downlevel.We are considering all the options here and it is too early to say exactly how hw accel is going to work on different platforms..