On Tue, Mar 22, 2011 at 11:55:59AM -0700, Matthew Fleming wrote: > On Tue, Mar 22, 2011 at 11:12 AM, Kostik Belousov <[email protected]> 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@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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