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



On 6/29/2012 4:23 PM, Rolu wrote:
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.


SO, what DomU are you using? That means you were able to install the Video drivers inside the DomU for your HD6670 card and you can reboot the DomU without issues and video still works?


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.

Ya, so far i have not read or heard about this feature, BUT i know the FLR rest issues is quite the problem with Windows VMs, probably the same thing i am having issues with not working. Once i boot into Win7, install the ATI drivers, than reboot the DomU, and it just hangs at the "Starting Windows" black screen and never gets past it. I have read a bunch of things and will do more trial and error things, but for now just wondered about that "FLReset+" as stated on Wiki.

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