Re: [Xen-devel] [PATCH 1/3] libxl: attach xen-pciback only to PV domains

[Juergen Schinker <ba1020@xxxxxxxxxxxxxxxxxxx>]

----- On 18 Oct, 2016, at 21:03, Marek Marczykowski-Górecki 
marmarek@xxxxxxxxxxxxxxxxxxxxxx wrote:

> On Tue, Oct 18, 2016 at 04:52:29PM -0400, Konrad Rzeszutek Wilk wrote:
>> On Tue, Oct 18, 2016 at 03:53:31AM +0200, Marek Marczykowski-Górecki wrote:
>> > HVM domains use IOMMU and device model assistance for communicating with
>> > PCI devices, xen-pcifront/pciback is used only in PV domains.
>> > When HVM domain has device model in stubdomain, attaching xen-pciback to
>> > the target domain itself is not only useless, but also may prevent
>> > attaching xen-pciback to the stubdomain, effectively breaking PCI
>> > passthrough.
>> 
>> This has the consequence that the "reset" of the device that
>> pciback does will no longer be done.
>> 
>> That is the FLR functionality will not be exercised anymore.
> 
> Are you sure about that? libxl__device_pci_add calls
> libxl__device_pci_reset, regardless of my patch.
 
does this mean that you don't need a FLR+ capable graphics card for pass-throu ?

that is what is stopping me from doing a passthrou - my goal is to have my 
Desktop on a VM

start an X-Server with direct access to the gfx with according performance

I use this one with passive cooling

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. 
[AMD/ATI] Cape Verde PRO [Radeon HD 7750/8740 / R7 250E]

Juergen

are you the same Marek from Qubes?

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