SFXGE_TX_DESCSIZE
SFXGE_TX_DESCSIZE - page_off;
#define SFXGE_TX_DESCOFFSET (SFXGE_TX_DESCSIZE - 1)
size = MIN(SFXGE_TX_DESCSIZE - stmp->stm_off, dmac.dmac_size);
size = MIN(SFXGE_TX_DESCSIZE, dmac.dmac_size);