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Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups |
Date: |
Tue, 23 Mar 2010 12:47:24 +0200 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Mon, Mar 22, 2010 at 08:16:01PM -0500, Anthony Liguori wrote:
> On 03/22/2010 07:49 PM, Paul Brook wrote:
>>> Solutions:
>>> - VirtIOPCIBus and hang devices from there (anthony). Why? because
>>> this is a simulated pci bus, we can implement the features that we
>>> need (not full pci) in the three showed architectures. We will have
>>> VirtIOPCIBLock everywhere, and its VirtIOPCIBus implmentation will
>>> hide the details.
>>>
>> This is not how I understood Anthony's proposal.
>>
>> VirtIOPCIBus makes no sense. The whole reason we have this problem is because
>> the VirtIO devices can not make any assumptions about the bus they are
>> connected to.
>>
>> The key point is that we promote VirtIO devices to nodes in the device tree.
>> i.e. VirtIODevice descends directly from DeviceState.
>>
>> Instead of trying to make a single polymorphic hybryd object, split into
>> separate objects for the component parts. Each host binding (PCI, syborg,
>> s390, etc.) provides a single VirtIO bridge device. This includes a
>> VirtIOBus,
>> to which the VirtIODevice is attached.
>>
>> Most of the code and abstraction layers for this are already there.
>> We just replace virtio_bind_device with VirtIOBus, add direct registration of
>> VirtIODevice, and rip out all the crufty old device specific bits from
>> virtio-
>> pci.c.
>>
>
> Right. The only real challenge is dealing with legacy save/restore and
> command line syntax. For save/restore, we can possibly have a dummy
> device that can split the VirtioPCI device state from the virtio device
> states and do the right thing.
>
> I'm not sure what we should do for command line syntax. We can keep
> -drive working as is. Do we need to support -device based creation? I
> don't think we've really considered what to do in a situation like this.
>
> Regards,
>
> Anthony Liguori
If we need to change command line because of an implementation
change, IMO something is wrong with the design.
Users shouldn't care about non-existent virtio bus.
>>
>>
>>> - having multiple inheritance is "more natural" to virtio, then we have
>>> to change all the system to be able to allow multiple inherintance,
>>> even if it is more complex, and nothing else uses/needs it (mst).
>>>
>> I'm not convinced multiple inheritance solves the real problem, much less
>> that
>> it is worthwhile.
>>
>> Paul
>>
>>
>>
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, (continued)
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Anthony Liguori, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Paul Brook, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Anthony Liguori, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Paul Brook, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Anthony Liguori, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Paul Brook, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Michael S. Tsirkin, 2010/03/22
- [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Juan Quintela, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Paul Brook, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Anthony Liguori, 2010/03/22
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups,
Michael S. Tsirkin <=
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Gerd Hoffmann, 2010/03/23
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Paul Brook, 2010/03/23
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Michael S. Tsirkin, 2010/03/23
- [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Juan Quintela, 2010/03/23
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Michael S. Tsirkin, 2010/03/21
- [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Juan Quintela, 2010/03/21
- [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Michael S. Tsirkin, 2010/03/22
- [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Michael S. Tsirkin, 2010/03/18
- Re: [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Gerd Hoffmann, 2010/03/18
- [Qemu-devel] Re: [PATCH 0/9] Virtio cleanups, Juan Quintela, 2010/03/18