From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: iommu=dom0-passthrough behavior Date: Fri, 16 Nov 2012 08:22:38 +0000 Message-ID: <50A605DE02000078000A9230@nat28.tlf.novell.com> References: <5097DB9102000078000A65C7@nat28.tlf.novell.com> <50A20DE302000078000A7F6B@nat28.tlf.novell.com> <50A223DE02000078000A7FE6@nat28.tlf.novell.com> <50A23C0C02000078000A8085@nat28.tlf.novell.com> <50A2755402000078000A837D@nat28.tlf.novell.com> <50A3AD4E02000078000A87BD@nat28.tlf.novell.com> <50A4BE6D02000078000A8B89@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Xiantao Zhang , Yang Z Zhang Cc: "wei.huang2@amd.com" , "weiwang.dd@gmail.com" , xen-devel List-Id: xen-devel@lists.xenproject.org >>> On 16.11.12 at 07:21, "Zhang, Xiantao" wrote: >> >> Which, if I'm not mistaken, could be implemented entirely independent >> >> of "iommu=dom0-passthrough". I'll see if that helps on the offending >> system. >> > >> > I mean this one: >> >>>c) we could provide a command line option to allow fake devices to be >> >>>create >> > >> > Yes, I don't think "iommu=dom0-passthrough" can meet your requirement. >> > We had better add a cmd line option to pass the related information >> > to hypervisor and VT-d can create the pass-through context entry for >> > the undetectable device. >> >> You misunderstood: What I was saying (and seeking confirmation) is that I >> don't think the new command line option would need to have any >> connection to the existing, non-suitable one. In particular, for it to take > effect, >> "iommu=dom0-passthrough" >> wouldn't need to be specified at all. > Okay. Back to your customer's issue, I don't think we have a clean solution > if the device can't be detected by hypervisor. We only can figure out how > to workaround this issue through a new command line option. > BTW, if the device can't be detected, how to load its driver by OS ? Once again - the device a function 0 is being detected, but when the driver loads we see at least on DMA operation with a source ID of function 1 under the same bus and slot. There's no driver needed for the phantom device at function 1. Jan