Message-ID: <49D45F59.9030100@redhat.com>
Date: Thu, 02 Apr 2009 09:46:49 +0300
From: Avi Kivity <avi@redhat.com>
User-Agent: Thunderbird 2.0.0.21 (X11/20090320)
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To: Herbert Xu <herbert@gondor.apana.org.au>
CC: Anthony Liguori <anthony@codemonkey.ws>, andi@firstfloor.org,
       ghaskins@novell.com, linux-kernel@vger.kernel.org, agraf@suse.de,
       pmullaney@novell.com, pmorreale@novell.com, rusty@rustcorp.com.au,
       netdev@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [RFC PATCH 00/17] virtual-bus
References: <20090402030935.GA27836@gondor.apana.org.au>
In-Reply-To: <20090402030935.GA27836@gondor.apana.org.au>
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Herbert Xu wrote:
> Anthony Liguori <anthony@codemonkey.ws> wrote:
>   
>> That said, I don't think we're bound today by the fact that we're in 
>> userspace.  Rather we're bound by the interfaces we have between the 
>> host kernel and userspace to generate IO.  I'd rather fix those 
>> interfaces than put more stuff in the kernel.
>>     
>
> I'm sorry but I totally disagree with that.  By having our IO
> infrastructure in user-space we've basically given up the main
> advantage of kvm, which is that the physical drivers operate in
> the same environment as the hypervisor.
>   

I don't understand this.  If we had good interfaces, all that userspace 
would do is translate guest physical addresses to host physical 
addresses, and translate the guest->host protocol to host API calls.  I 
don't see anything there that benefits from being in the kernel.

Can you elaborate?

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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