Add new CheckComposite hook. This allows a driver to avoid the migration of

pixmaps for a Composite operation if the operation can't be supported.
    This hook is optional.

hw/kdrive/src/kaapict.c

@@ -426,6 +426,11 @@ kaaTryDriverComposite(CARD8		op,
 				   width, height))
 	return 1;
 
+    if (pKaaScr->info->CheckComposite &&
+	!(*pKaaScr->info->CheckComposite) (op, pSrc, pMask, pDst))
+    {
+	return -1;
+    }
 
     if (pSrc->pDrawable->type == DRAWABLE_PIXMAP)
 	kaaPixmapUseScreen ((PixmapPtr) pSrc->pDrawable);

hw/kdrive/src/kdrive.h

@@ -348,6 +348,10 @@ typedef struct _KaaScreenInfo {
 			  int	height);
     void	(*DoneBlend) (void);
 
+    Bool        (*CheckComposite) (int		op,
+				   PicturePtr	pSrcPicture,
+				   PicturePtr	pMaskPicture,
+				   PicturePtr	pDstPicture);
     Bool        (*PrepareComposite) (int		op,
 				     PicturePtr		pSrcPicture,
 				     PicturePtr		pMaskPicture,