Re: [Xen-devel] How vital is having "FLReset+" for VGA Passthru in DomU?

[Rolu <rolu@xxxxxxxx>]

On Fri, Jun 29, 2012 at 9:44 PM,  <cyberhawk001@xxxxxxxxx> wrote:
> I was reading the Wiki page here: http://wiki.xen.org/wiki/VTd_HowTo don't
> know how updated it is, BUT at the top it said:
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> Xen 4.1 xl tools notes
>
> Only devices with FLR capabilities are supported.
> Passing through a PCI card without FLR capability will result an error.
>
> To check if your PCI devices have FLR function, check in this wiki, [How can
> I check if PCI device supports FLR (Function Level Reset) ?]
>
> If you see output with "FLReset-" then your PCI device don't support FLR
> function. If output have "FLReset+" then it does.
>
> As this time of writing, June 2012, there are very very few PCI devices
> support FLR function.
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>
> THAN was reading here:
> http://wiki.xen.org/wiki/Xen_PCI_Passthrough#How_can_I_check_if_PCI_device_supports_FLR_.28Function_Level_Reset.29_.3F
> at the bottom of the page where it says:
>
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>
> How can I check if PCI device supports FLR (Function Level Reset)?
>
> Run "lspci -vv" (in dom0) and check if the device has "FLReset+" in the
> DevCap field.
>
> If you are Ubuntu/Debian user don't forget to add sudo at front, otherwise,
> you won't get the result you should get.
>
> sudo lspci -vv | egrep -i --colour flreset
>
> The above line should get root access for lspci program and show colour with
> flreset it found from output
>
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> I did that and ALL of my devices it listed showed "FLReset-", there were
> only 3x "Etron Technology, Inc. EJ168 USB3.0" controllers that showed
> "FLReset+"
>
> SO, I have been trying to get my ATI FirePro V7900 Video Card to passthru to
> a Windows 7 Ultimate DomU with no luck so far AND was wondering how critical
> was for that device to show as "FLReset+"?
>
> 1.) Since my VGA card and AUDIO component of it, shows up as "FLReset-",
> does that mean it is impossible to get it fully working in a Win7 DomU?

I have a video card (Radeon HD 6670) with FLReset- passed through to a
linux domU as a secondary video card (i.e. it boots from the built in
emulated card, not the Radeon) and it works. The FLReset doesn't seem
mandatory.

I am running the latest xen 4.2 unstable though.

> 2.) Does having the feature "FLReset+" depend on the motherboard BIOS,
> motherboard hardware or the BIOS onboard the Video Card that could be
> updated to get back the "FLReset+" so you can have the FLR reset
> functionality?

I think it depends on the card's hardware. It has to implement this
functionality. A firmware update for the card could maybe add it, but
I haven't heard of any that do.

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