void bmdma_cmd_writeb(BMDMAState *bm, uint32_t val) { #ifdef DEBUG_IDE printf("%s: 0x%08x\n", __func__, val); #endif /* Ignore writes to SSBM if it keeps the old value */ if ((val & BM_CMD_START) != (bm->cmd & BM_CMD_START)) { if (!(val & BM_CMD_START)) { /* * We can't cancel Scatter Gather DMA in the middle of the * operation or a partial (not full) DMA transfer would reach * the storage so we wait for completion instead (we beahve * like if the DMA was completed by the time the guest trying * to cancel dma with bmdma_cmd_writeb with BM_CMD_START not * set). * * In the future we'll be able to safely cancel the I/O if the * whole DMA operation will be submitted to disk with a single * aio operation with preadv/pwritev. */ if (bm->bus->dma->aiocb) { qemu_aio_flush(); assert(bm->bus->dma->aiocb == NULL); assert((bm->status & BM_STATUS_DMAING) == 0); } } else { bm->cur_addr = bm->addr; if (!(bm->status & BM_STATUS_DMAING)) { bm->status |= BM_STATUS_DMAING; /* start dma transfer if possible */ if (bm->dma_cb) bm->dma_cb(bmdma_active_if(bm), 0); } } } bm->cmd = val & 0x09; }