DMA controller on Northbridge?

[Kostik Belousov]

On Tue, Mar 22, 2011 at 11:55:59AM -0700, Matthew Fleming wrote:
> On Tue, Mar 22, 2011 at 11:12 AM, Kostik Belousov <kostikbel at gmail.com> wrote:
> > On Tue, Mar 22, 2011 at 10:11:04AM -0700, Matthew Fleming wrote:
> >> How can I tell if the Northbridge on a machine has a built-in DMA
> >> controller?  And if it does, what device would I use to control it?
> >>
> >> I ask because I'm working with a PCI card that has a 36-bit physical
> >> address limit, and that means bounce buffers when using more than 64GB
> >> of memory.  I'd prefer not to use bounce buffers, and since the card's
> >> memory that I'm using is mapped into the physical space of the FreeBSD
> >> host, the entire address space of the card that I care about is
> >> available to FreeBSD.  So while pio to the card's memory is too slow
> >> to be useful, if there was a way to use a DMA controller on the
> >> motherboard to get data into and out of the card, that may be
> >> preferable to using the card's DMAC with the limited address space.
> >>
> >> But all that's just theory -- I have no idea how to tell whether the
> >> mobo has a DMAC, and if it does, how to control it.  Help? :-)
> >>
> >> Attached is the boot dmesg; I can also run pciconf commands, etc., to
> >> help out with figuring out what I have.
> >
> > I believe what are you looking for is
> > ftp://download.intel.com/technology/.../Intel(r)_VT_for_Direct_IO.pdf
Oops.

ftp://download.intel.com/technology/computing/vptech/Intel(r)_VT_for_Direct_IO.pdf

> 
> This link doesn't work for me.
> 
> > On my X58 machine it is shown like this:
> > none6 at pci0:0:22:2:   class=0x088000 card=0xf38015d9 chip=0x34328086 rev=0x12 hdr=0x00
> >    vendor     = 'Intel Corporation'
> >    device     = 'DMA Engine'
> >    class      = base peripheral
> >    cap 11[80] = MSI-X supports 1 message in map 0x10
> >    cap 10[90] = PCI-Express 2 root endpoint max data 128(128) link x0(x0)
> >    cap 01[e0] = powerspec 3  supports D0 D3  current D0
> 
> I do seem to have several DMA Engine entries in pciconf on this
> hardware.  Hopefully the above doc will explain what to do. :-)
> 
> Thanks,
> matthew
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