can a valid bus_dma_tag_t be NULL ?

[M. Warner Losh]

In message: <20070219224006.GC73385 at funkthat.com>
            John-Mark Gurney <gurney_j at resnet.uoregon.edu> writes:
: >         if (bus_dma_tag_create(NULL, 4, 0, BUS_SPACE_MAXADDR_32BIT,
: 				 ^^^^
: This is incorrect, and should be: bus_get_dma_tag(dev), though that is
: correct for -stable, (or have we introduced bus_get_dma_tag into -stable?)

There's currently a compat shim:

#define bus_get_dma_tag(dev) NULL

so you shuold use it for both -current and -stable.

Warner