How to debug >2GB memory issues (and 3ware)

[James R. Van Artsalen]

Vinod Kashyap wrote:

>The 3ware driver (twe) for 7xxx/8xxx controllers can handle upto
>4 GB memory on FreeBSD 4.x, and beyond 4 GB on FreeBSD 5.x.  The
>driver (twa) for 9xxx controllers can handle memory beyond 4 GB
>on both 4.x and 5.x.
>  
>

The twe driver in MAIN seems to be limited to direct access to the lower 
4GB.  Am I misinterpreting the significance of this code in twe_freebsd.c?

    /*
     * Allocate the parent bus DMA tag appropriate for PCI.
     */
    if (bus_dma_tag_create(NULL, 				/* parent */
			   1, 0, 				/* alignment, boundary */
			   BUS_SPACE_MAXADDR_32BIT, 		/* lowaddr */
			   BUS_SPACE_MAXADDR, 			/* highaddr */
			   NULL, NULL, 				/* filter, filterarg */
			   MAXBSIZE, TWE_MAX_SGL_LENGTH,	/* maxsize, nsegments */
			   BUS_SPACE_MAXSIZE_32BIT,		/* maxsegsize */
			   BUS_DMA_ALLOCNOW,			/* flags */
			   NULL,				/* lockfunc */
			   NULL,				/* lockarg */