From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexander Graf <agraf@suse.de>
Subject: Re: [RFC] Unify KVM kernel-space and user-space code into a single
 project
Date: Wed, 24 Mar 2010 15:24:00 +0100
Message-ID: <4BAA2080.5020902@suse.de>
References: <4BA7B9E0.5080009@codemonkey.ws> <20100322192739.GE21919@elte.hu> <4BA7C96D.2020702@redhat.com> <4BA7E9D9.5060800@codemonkey.ws> <20100323140608.GJ1940@8bytes.org> <4BA8EEDE.8070309@redhat.com> <20100323182153.GA14800@8bytes.org> <4BA99BCB.5080501@redhat.com> <20100324115900.GB14800@8bytes.org> <4BAA00B1.20407@redhat.com> <20100324125043.GC14800@8bytes.org> <4BAA0DFE.1080700@redhat.com> <4BAA1946.6060703@suse.de> <4BAA1ADD.9090502@redhat.com>
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Cc: Joerg Roedel <joro@8bytes.org>,
	Anthony Liguori <anthony@codemonkey.ws>,
	Ingo Molnar <mingo@elte.hu>,
	Pekka Enberg <penberg@cs.helsinki.fi>,
	"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Sheng Yang <sheng@linux.intel.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Jes Sorensen <Jes.Sorensen@redhat.com>,
	Gleb Natapov <gleb@redhat.com>, ziteng.huang@intel.com,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Fr?d?ric Weisbecker <fweisbec@gmail.com>,
	Gregory Haskins <ghaskins@novell.com>
To: Avi Kivity <avi@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <4BAA1ADD.9090502@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

Avi Kivity wrote:
> On 03/24/2010 03:53 PM, Alexander Graf wrote:
>>
>>> Someone needs to know about the new guest to fetch its symbols.  Or do
>>> you want that part in the kernel too?
>>>      
>>
>> How about we add a virtio "guest file system access" device? The guest
>> would then expose its own file system using that device.
>>
>> On the host side this would simply be a -virtioguestfs
>> unix:/tmp/guest.fs and you'd get a unix socket that gives you full
>> access to the guest file system by using commands. I envision something
>> like:
>>    
>
> The idea is to use a dedicated channel over virtio-serial.  If the
> channel is present the file server can serve files over it.

The file server being a kernel module inside the guest? We want to be
able to serve things as early and hassle free as possible, so in this
case I agree with Ingo that a kernel module is superior.

>
>> SEND: GET /proc/version
>> RECV: Linux version 2.6.27.37-0.1-default (geeko@buildhost) (gcc version
>> 4.3.2 [gcc-4_3-branch revision 141291] (SUSE Linux) ) #1 SMP 2009-10-15
>> 14:56:58 +0200
>>
>> Now all we need is integration in perf to enumerate virtual machines
>> based on libvirt. If you want to run qemu-kvm directly, just go with
>> --guestfs=/tmp/guest.fs and perf could fetch all required information
>> automatically.
>>
>> This should solve all issues while staying 100% in user space, right?
>>    
>
> Yeah, needs a fuse filesystem to populate the host namespace (kind of
> sshfs over virtio-serial).

I don't see why we need a fuse filesystem. We can of course create one
later on. But for now all you need is a user connecting to that socket.


Alex