MSK_MAXTXSEGS
MSK_MAXTXSEGS, /* nsegments */
bus_dma_segment_t txsegs[MSK_MAXTXSEGS];
m = m_collapse(*m_head, M_NOWAIT, MSK_MAXTXSEGS);
#define MSK_RESERVED_TX_DESC_CNT (MSK_MAXTXSEGS + 3)