Re: virtio & hypercall interface?

[Dor Laor <dor.laor-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Avi Kivity wrote:
> Anthony Liguori wrote:
>   
>> Dor Laor wrote:
>>   
>>     
>>>> Hi all,
>>>>
>>>> 	I've finally started looking at Dor's git tree, and it struck me
>>>>     
>>>>       
>>>>         
>>> that
>>>   
>>>     
>>>       
>>>> it conflicts with Anthony's hypercall patches.  FWIW I like Anthony's
>>>> patching thing, and don't really care about arg order.  It'd be nice if
>>>> we could pull in the same direction tho 8)
>>>>
>>>> Thanks,
>>>> Rusty.
>>>>     
>>>>       
>>>>         
>>> Good news you're looking at my tree, since the forum I didn't do much
>>> since I had to catch up some gazlion other tasks, never the less
>>> starting on Sunday I'm back again.
>>>
>>> Actually, I wanted to rebase my hypercalls over Anhtony's too (except
>>> for allowing userspace handling).
>>>     
>>>       
>> I thought we discussed just providing a signaling message to userspace 
>> for virtio?  It's not strictly necessary to expose hypercalls to 
>> userspace in order to implement a virtio backend in userspace.
>>
>>   
>>     
>
> Yes, that's what I'd like to see too.  Signal a channel.
>
>   
First, I though that this 
http://www.mail-archive.com/kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org/msg06230.html
was your latest opinion.
Second, regardless of the channel signal notification, there are still 
real necessities for userspace hypercall handling:
1. For virtio drivers there is also registration hypercall for passing 
the shared memory pfns.
    Sure there are other possibilities, but why limit ourselves?
2. For other purposes such as a balloon driver, a deflate/inflate 
hypercalls are needed.
    Although for x86 mmio/pio can be used but this is not compatible 
with other architectures.

Regards & thanks for the patch resend,
Dor

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