[vfio-users] Requesting USB Card Quad Bus advice

[Steve Freitas]

On 11/07/2017 06:51 AM, Alex Williamson wrote:
> On Mon, Nov 6, 2017 at 11:58 PM, Steve Freitas <sflist at ihonk.com 
> <mailto:sflist at ihonk.com>> wrote:
>
>     On 11/06/2017 07:01 PM, Marcial Ascencio wrote:
>
>         Hi guys, i was planning to buy USB card with at least 2 usb
>         ports to assign each one to each VM, so I'm asking some advice
>         about a brand that works soft with Linux VFIO. Thank you so
>         much in advance!
>
>
>     Hi Marcial,
>
>     The Sonnet Allegro Pro worked great for me:
>     https://amazon.com/Sonnet-Allegro-Pro-PCIe-card/dp/B00XPUHO10/
>     <https://amazon.com/Sonnet-Allegro-Pro-PCIe-card/dp/B00XPUHO10/>
>
>     I pass three of the four controllers through to different VMs, no
>     ACS override necessary on my machine. VM reboots work without an
>     issue. An earlier post on this mailing list indicated problems
>     with this card with VM reboots, but that seems to have been
>     resolved in more recent kernels. My host runs Ubuntu 17.04, kernel
>     4.10.
>
>
> Does the PCIe switch actually support ACS on the downstream ports for 
> this card?  I've seen some reports that certain switch configurations 
> are incorrectly allowing separate iommu groups where they shouldn't.  
> Fair warning, we're probably going to need to fix that and break some 
> configurations that were incorrectly grouped. Thanks,
>

Yer breakin' my heart! :-)

Good question, how do I check that?

Steve

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