On Fri, 01 Jun 2007, Andi Kleen wrote: > On Fri, Jun 01, 2007 at 03:38:57PM -0400, Rik van Riel wrote: > > Andi Kleen wrote: > > > > >An pci_map_sg failing typically leads to an IO error and we've > > >always printk'ed those. Otherwise people will wonder why they > > >get EIO. > > > > In some situations. In this case the qla2xxx driver uses > > the pci_map_sg() failure as a throttling mechanism and > > First WTF does it need swiotlb anyways? QA hardware should > be definitely DAC capable, shouldn't it?
yes, the card can support 64bit DMA transfers. but in this case the 'required' DMA mask returned from dma_get_required_mask() states that a 32bit mask would suffice. Here's a snippet from the bugzilla report (https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=219216): QLogic Fibre Channel HBA Driver PCI: Enabling device 0000:1f:00.0 (0140 -> 0143) ACPI: PCI Interrupt 0000:1f:00.0[A] -> GSI 16 (level, low) -> IRQ 16 qla2xxx 0000:1f:00.0: Found an ISP2432, irq 16, iobase 0xffffc20000020000 *** qla2x00_config_dma_addressing: required_mask set to 000000007fffffff. *** qla2x00_config_dma_addressing: required_mask has no high-dword bits set. *** qla2x00_config_dma_addressing: set consistent 64bit mask returned 0. *** qla2x00_config_dma_addressing: defaulting to 32bit mask/consistent-mask. qla2xxx 0000:1f:00.0: Configuring PCI space... Which tells me that a 32bit DMA mask is being set for dma_set_mask() and pci_set_consistent_dma_mask() since dma_get_required_mask() is returning back 7fffffff -- no upper-dword bits set... ... > > printing out all the warnings will actually slow down the > > system. > > Another reason is that there is a lot of code that > still doesn't check the return values and when that > happens you might get data corruption too. > > > > > Andi, what do you propose as a solution? > > A different interface; like I wrote in my earlier mail. > > Another probabibility would be to have a blocking interface > to swiotlb that won't fail. That would be the better solution > long term, but i was told it is hard to fit into some current > driver interfaces. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
