On Jun 11, 2010, at 10:47 AM, Scott Long wrote: > On Jun 11, 2010, at 11:44 AM, Marcel Moolenaar wrote: >> >> On Jun 11, 2010, at 10:37 AM, Scott Long wrote: >>> >>> I'm not clear why you even need bounce buffers for RX. The chip supports >>> 64bit addresses with no boundary or alignment restrictions. >> >> As per: >> /* >> * All controllers that are not 5755 or higher have 4GB >> * boundary DMA bug. >> * Whenever an address crosses a multiple of the 4GB boundary >> * (including 4GB, 8Gb, 12Gb, etc.) and makes the transition >> * from 0xX_FFFF_FFFF to 0x(X+1)_0000_0000 an internal DMA >> * state machine will lockup and cause the device to hang. >> */ >> if (BGE_IS_5755_PLUS(sc) == 0) >> sc->bge_flags |= BGE_FLAG_4G_BNDRY_BUG; >> >> and: >> lowaddr = BUS_SPACE_MAXADDR; >> if ((sc->bge_flags & BGE_FLAG_40BIT_BUG) != 0) >> lowaddr = BGE_DMA_MAXADDR; >> if ((sc->bge_flags & BGE_FLAG_4G_BNDRY_BUG) != 0) >> lowaddr = BUS_SPACE_MAXADDR_32BIT; >> /* >> * Allocate the parent bus DMA tag appropriate for PCI. >> */ >> error = bus_dma_tag_create(bus_get_dma_tag(sc->bge_dev), >> 1, 0, lowaddr, BUS_SPACE_MAXADDR, NULL, >> NULL, BUS_SPACE_MAXSIZE_32BIT, 0, BUS_SPACE_MAXSIZE_32BIT, >> 0, NULL, NULL, &sc->bge_cdata.bge_parent_tag); >> >> > > Noted in previous email. If this restriction is put in the boundary > attribute, then you'll only bounce the very rare case of an mbuf straddling a > 4G boundary.
I agree with you, but I was just giving the facts. I don't even know if we attempted to use the boundary argument before but problems forced us to resort to this. -- Marcel Moolenaar xcl...@mac.com _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
