This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] swiotlb=force in Konrad's xen-pcifront-0.8.2 pvops domU

To: "Lin, Ray" <Ray.Lin@xxxxxxx>
Subject: Re: [Xen-devel] swiotlb=force in Konrad's xen-pcifront-0.8.2 pvops domU kernel with PCI passthrough
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Fri, 12 Nov 2010 10:56:59 -0500
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Dante Cinco <dantecinco@xxxxxxxxx>
Delivery-date: Fri, 12 Nov 2010 07:59:10 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <EB4C61A1A2501842A04B573FE42B14D601374FBD2C@xxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <20101111190351.GB15530@xxxxxxxxxxxx> <EB4C61A1A2501842A04B573FE42B14D601374FBD2C@xxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.20 (2009-06-14)
On Thu, Nov 11, 2010 at 12:42:03PM -0700, Lin, Ray wrote:
> Konrad,
>    See my response in red.

Please don't top post.
> -Ray
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Konrad Rzeszutek 
> Wilk
> Sent: Thursday, November 11, 2010 11:04 AM
> To: Dante Cinco
> Cc: Xen-devel
> Subject: Re: [Xen-devel] swiotlb=force in Konrad's xen-pcifront-0.8.2 pvops 
> domU kernel with PCI passthrough
> On Thu, Nov 11, 2010 at 10:31:48AM -0800, Dante Cinco wrote:
> > Konrad,
> >
> > Without swiotlb=force, I don't see "PCI-DMA: Using software bounce
> > buffering for IO" in /var/log/kern.log.
> >
> > With iommu=soft and without swiotlb=force, I see the "software bounce
> > buffering" in /var/log/kern.log and an NMI (see below) when I load the
> > kernel module drivers. I made sure the NMI is reproducible and not a
> What is the kernel module doing to cause this? DMA?

??? What did it do?

> > one-time event.
> So doing 64-bit DMA causes an NMI. Do you have the Hypervisor's IOMMU VT-d 
> enabled or disabled? (iommu=off,verbose) If you turn it off does this work?
> We have IOMMU VT-d enabled. If we turn it off (iommu=off,verbose), the DMA 
> doesn't work properly and the driver code is unable to detect the source of 
> interrupt. The interrupts of our device would be disabled by kernel 
> eventually due to nobody services the interrupts for more than 100000 times.

That does not sound right. You should be able to use the PCI passthrough 
without the IOMMU. Since it
is an interrupt issue it sounds like that you are using x2APIC and that is 
enabled without the IOMMU.
Had you tried disabling IOMMU and x2apic? (this is all on the hypervisor line?)

Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>