On Fri, 31 Mar 2017 13:36:36 -0700 Joshua Hoblitt <[email protected]> wrote:
> On 03/31/2017 01:22 PM, Alex Williamson wrote: > >> which does claim ACS support in the overview sheet. Does anyone know if > >> ACS is indeed working with the "pex 8747" and/or the sm x1?sat series of > >> motherboards? Alternatively, does anyone know of an E3-1200 motherboard > >> that does have working ACS with 2x [8x/16x] PCIe slots? > > The end-to-end topology needs to support ACS, so it really does not > > matter if a switch between the endpoint and the root port supports ACS > > if the upstream root port does not. Packets could be rerouted at the > > root port regardless of how much isolation exists downstream of it. > Well shoot, I obviously hadn't grasped that. ;( > >> If anyone has followed my rambling this far, thank you for your extreme > >> patience. I would like to thank Alex Williamson for his vfio blog and > >> the kvmforum talk up on youtube -- I would be completely lost at this > >> point without that information. > > Thanks! I certainly discourage use of the ACS override patch, which > > at least for my part is why you don't see forward ports of it. AFAIK, > > it's not possible to get separate IOMMU groups for the processor root > > ports on i3/5/7/E3 otherwise though. If you need to stick with this > > product family, you'll need to figure out how to make a configuration > > where the processor root ports are used exclusively by either the host > > or the guest. We do have ACS equivalent isolation in the PCH root > > ports, but of course that moves you further from the CPU and might > > restrict full bandwidth. Otherwise you need a Xeon E5 or High End > > Desktop processor. As I document in my setup, I use IGD for host > > graphics and can therefore dedicate the processor root port to the > > guest graphics. I can use the PCH root ports for a 3rd guest if > > necessary. > I don't believe there is an IGD configuration that would work for me as > I need to drive 3x 1920x1200 displays. The displays I have (total of 6) > are all DP1.2, which means I need at least least 1 MST capable DP + > another port (DP1.2 doesn't have enough bandwidth for 3 displays at that > resolution). I had an issue with monitors randomly not going into > powersave when daisy chained via MST and have switched to using 3 fully > independent DPs. > > Do you know if all E5s have ACS on the root port -- including the low > end E5-1600v4 family? The same data sheet covers the E5-4600, 2600, and 1600 processors and indicates ACS support. Unless I've missed a footnote somewhere, I'd think that means even the low end E5s have ACS. Thanks, Alex _______________________________________________ vfio-users mailing list [email protected] https://www.redhat.com/mailman/listinfo/vfio-users
