New handling of privates [was: Re: xf86-video-intel 2.5 release planning]

Eamon Walsh ewalsh at
Fri Aug 1 15:21:47 PDT 2008

Keith Packard wrote:
> On Fri, 2008-08-01 at 13:56 -0400, Eamon Walsh wrote:
>> Yes, this consolidation should be done.  I also have the OK from Peter 
>> to remove some DIX-level keys associated with the MPX merge.  And 
>> lately, a lot of code has been dropped from master which has cut down on 
>> the number of keys.
> The private indicies should be allocated per object-type instead of
> globally; that way you'd only deal with the number of privates that
> could be instantiated on a particular object.
> That's the way it used to work.

The per-object-type support was dropped because under the current 
linked-list implementation it isn't necessary; each object's list 
contains only the privates that have been referenced.

Going back to a fixed array will cause a "sparse" situation with unused 
spaces in the array (4 bytes per key-not-in-use per object).  Tomas has 
noted that it's possible to combine keys in many cases, so that instead 
of three keys for separate object types there would only be one.  But 
yeah, I guess with millions or billions or whatever of pixmaps, the 
wasted space could add up.

I think I know how to add per-object-type support back without breaking 
things.  Let's get the O(1) lookup done first.

Eamon Walsh <ewalsh at>
National Security Agency

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