On Thu, Oct 9, 2008 at 7:40 PM, FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote: > On Thu, 09 Oct 2008 16:05:57 -0700 > Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > >> Grant Grundler wrote: >> > On Thu, Oct 09, 2008 at 02:51:32PM -0700, Yinghai Lu wrote: >> >> On Thu, Oct 9, 2008 at 2:35 PM, Matthew Wilcox <matthew@xxxxxx> wrote: >> >>> Why's that interesting to the sysadmin of the machine? To the driver >> >>> writer, certainly. But what's the use of it to the people using the >> >>> machine? >> > ... >> >> make linux kernel act like black box as other os? >> > >> > I don't understand your reply. >> > If someone thinks linux is a black box, printing this message won't help them. >> > >> could find out easily why some driver doesn't set dma mask correctly. >> like why >> qlogic qla2xxx only set consistent to 64bit, >> emulex lpfc not set consistent to 64bit > > IIRC, except for one SGI architecture, coherent_dma_mask is > meaningless, dma_mask is always equal to coherent_dma_mask. Lots of > IOMMU implementations ignore coherent_dma_mask and use dma_mask for > alloc_coherent(). Some drivers doesn't set up coherent_dma_mask. ehci_hcd 0000:00:02.1: using 31bit consistent DMA mask ==> ck804 ehci, is using 31bit for consistent dma mask, at still use 32 bit for dma mask. qlogic qla2xxx and emulex lpfc dma mask and consistent_dma_mask is different... could have some story for them at least gart iommu is honoring the consistent dma mask. by calling dma_alloc_coherent_mask(dev, flag) if device could use 64 bit coherent dma mask, that is driver problem... print it out could put them in focus. YH -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
