Messages in this thread | | | Date | Mon, 15 Sep 2003 10:47:22 +0200 | From | Jens Axboe <> | Subject | Re: SII SATA request size limit |
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On Fri, Sep 12 2003, Eduardo Casino wrote: > Hi All, > > I had a look at the NetBSD pciide.c driver and found this interesting > bit of code: > > /* > * Rev. <= 0x01 of the 3112 have a bug that can cause data > * corruption if DMA transfers cross an 8K boundary. This is > * apparently hard to tickle, but we'll go ahead and play it > * safe. > */ > if (PCI_REVISION(pa->pa_class) <= 0x01) { > sc->sc_dma_maxsegsz = 8192; > sc->sc_dma_boundary = 8192; > } > > This is basically the same as setting hwif->rqsize to 15, but the NetBSD
You can do much much better than that, it's pretty simply to just restrict the segment size and boundary if you have a controller with such a bug. And then you get the benefit of the larger requests too, it's basically not a performance hit at that point.
-- Jens Axboe
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