Messages in this thread | | | Subject | Re: PCIe device driver question | From | "V.Radhakrishnan" <> | Date | Wed, 30 Jul 2008 22:21:37 +0530 |
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> > am testing this in an X86_64 architecture machine with 4 GB of RAM. I > > am able to successfully dma data into any memory (dma) address > > > 0x0000_0001_0000_0000.
How can you DMA "successfully" into this address which is > 4 GB when you have only 4 GB RAM ? Or am I missing something ?
V. Radhakrishnan http://www.atr-labs.com
On Wed, 2008-07-30 at 09:09 -0700, Sanka Piyaratna wrote: > Hi Alan, > > Actually the failures occur at addresses lot higher than this range, I am noticing the failure at dma address 0x0000000037845000. This would be at around 900MB ? > > Thanks > > Sanka > > > > ----- Original Message ---- > From: Alan Cox <alan@lxorguk.ukuu.org.uk> > To: Sanka Piyaratna <cesanka@yahoo.com> > Cc: linux-kernel@vger.kernel.org > Sent: Thursday, 31 July, 2008 1:17:18 AM > Subject: Re: PCIe device driver question > > On Wed, 30 Jul 2008 09:00:58 -0700 (PDT) > Sanka Piyaratna <cesanka@yahoo.com> wrote: > > > Hi, > > > > I am currently developing a PCIe data capture card hardware and the > > device drivers to drive this. I have implemented DMA on the data > > capture and the scatter-gather DMA is implemented in the hardware. I > > am testing this in an X86_64 architecture machine with 4 GB of RAM. I > > am able to successfully dma data into any memory (dma) address > > > 0x0000_0001_0000_0000. However, my problem is to dma data to any > > address less than this. When I try to DMA data to an address less than > > 0x0000_0001_0000_0000, the hardware device hangs indicating that the > > address does not exist. > > Assuming the failures are in the range 640K-1MB then I would imagine your > bridge doesn't permit transfers via DMA to the ISA hole. > > > > Find a better answer, faster with the new Yahoo!7 Search. www.yahoo7.com.au/search > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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