From: Muli Ben-Yehuda <muli@il.ibm.com>
To: Sheng Yang <sheng@linux.intel.com>
Cc: Simon Horman <horms@verge.net.au>, Alexander Graf <agraf@suse.de>,
Chris Wright <chrisw@sous-sol.org>, Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Dmitri Seletski <drjoms@gmail.com>
Subject: Re: [PATCH qemu-kvm] device assignment: default requires IOMMU
Date: Thu, 24 Dec 2009 09:37:07 +0200 [thread overview]
Message-ID: <20091224073706.GA2475@il.ibm.com> (raw)
In-Reply-To: <200912241456.00624.sheng@linux.intel.com>
On Thu, Dec 24, 2009 at 02:56:00PM +0800, Sheng Yang wrote:
> > > >And, of course, disabling the IOMMU requirement using the old:
> > > >
> > > > -pcidevice host=[addr],dma=none
> > > >
> > > >or the newer:
> > > >
> > > > -device pci-assign,host=[addr],iommu=0
> > > >
> > > >will do what it always did (not require an IOMMU, and fail to work
> > > >properly).
> > >
> > > Yay!
> >
> > Sounds good to me. Though I am curious to know the reasoning
> > behind the current logic.
> >
> Sounds pretty good. :)
>
> I think maybe it due to we are interested in implementing PV DMA?
Yes, we are. The current defaults came from the desire to support both
pvdma and also 1-1 host mappings. There were patches floating around
for both. Having said that, I fully agree with this change---the
default should be to require IOMMU. Anything else is "highly
experimental".
Cheers,
Muli
next prev parent reply other threads:[~2009-12-24 7:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-23 22:40 [PATCH qemu-kvm] device assignment: default requires IOMMU Chris Wright
2009-12-24 0:45 ` Alexander Graf
2009-12-24 6:51 ` Simon Horman
2009-12-24 6:56 ` Sheng Yang
2009-12-24 7:37 ` Muli Ben-Yehuda [this message]
2009-12-24 7:41 ` Simon Horman
2009-12-24 11:35 ` Marcelo Tosatti
2010-01-18 14:18 ` Alexander Graf
2010-01-18 14:20 ` Avi Kivity
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