VBD_VA_SIZE
KASSERT(bcount + xbd_io->xio_start_offset <= VBD_VA_SIZE);
VBD_VA_SIZE, 0, UVM_KMF_VAONLY|UVM_KMF_WAITVA);
VBD_VA_SIZE, UVM_KMF_VAONLY);
#define VBD_MAX_INDIRECT_SEGMENTS (VBD_VA_SIZE >> PAGE_SHIFT)