On Tue, Mar 22, 2011 at 11:12 AM, Kostik Belousov <kostik...@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
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 _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
