Message-ID: <4AAF8966.3040602@redhat.com>
Date: Tue, 15 Sep 2009 15:32:38 +0300
From: Avi Kivity <avi@redhat.com>
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To: "Michael S. Tsirkin" <mst@redhat.com>
CC: Gregory Haskins <gregory.haskins@gmail.com>,
       "Ira W. Snyder" <iws@ovro.caltech.edu>, netdev@vger.kernel.org,
       virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
       linux-kernel@vger.kernel.org, mingo@elte.hu, linux-mm@kvack.org,
       akpm@linux-foundation.org, hpa@zytor.com,
       Rusty Russell <rusty@rustcorp.com.au>, s.hetze@linux-ag.com
Subject: Re: [PATCHv5 3/3] vhost_net: a kernel-level virtio server
References: <cover.1251388414.git.mst@redhat.com> <20090827160750.GD23722@redhat.com> <20090903183945.GF28651@ovro.caltech.edu> <20090907101537.GH3031@redhat.com> <20090908172035.GB319@ovro.caltech.edu> <4AAA7415.5080204@gmail.com> <20090913120140.GA31218@redhat.com> <4AAE6A97.7090808@gmail.com> <20090914164750.GB3745@redhat.com>
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On 09/14/2009 07:47 PM, Michael S. Tsirkin wrote:
> On Mon, Sep 14, 2009 at 12:08:55PM -0400, Gregory Haskins wrote:
>    
>> For Ira's example, the addresses would represent a physical address on
>> the PCI boards, and would follow any kind of relevant rules for
>> converting a "GPA" to a host accessible address (even if indirectly, via
>> a dma controller).
>>      
> I don't think limiting addresses to PCI physical addresses will work
> well.  From what I rememeber, Ira's x86 can not initiate burst
> transactions on PCI, and it's the ppc that initiates all DMA.
>    

vhost-net would run on the PPC then.

>>>   But we can't let the guest specify physical addresses.
>>>        
>> Agreed.  Neither your proposal nor mine operate this way afaict.
>>      
> But this seems to be what Ira needs.
>    

In Ira's scenario, the "guest" (x86 host) specifies x86 physical 
addresses, and the ppc dmas to them.  It's the virtio model without any 
change.  A normal guest also specifis physical addresses.

-- 
error compiling committee.c: too many arguments to function

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