[Lguest] [kvm-devel] [PATCH 6/6] virtio ring helper

[Avi Kivity]

Rusty Russell wrote:
> On Sun, 2007-09-23 at 12:05 +0200, Avi Kivity wrote:
>   
>> Rusty Russell wrote:
>>     
>>> On Thu, 2007-09-20 at 14:43 +0200, Avi Kivity wrote:  
>>>       
>>>> 32 bits of page numbers give 44 bits of physical address on x86.  That's 
>>>> 16TB per guest.  Admittedly it's smaller on a VAX.
>>>>         
>>> I like to feel that I make these mistakes to ensure others are paying
>>> attention.  However, it does mean that I can just put an address in
>>> there and increase the length field to 32 bits.  Much rejoicing.
>>>   
>>>       
>> Why are we sending page numbers anyway?  See below.
>>     
>
> Perhaps I was unclear.  I already changed to a 64-bit address.  I
> haven't send out another set of patches because I'm changing to Arnd's
> explicit virtio bus too.  Will send out a new set tomorrow at this rate.
>
>   

It does say so quite explicitly in the quoted text.  Sorry.

>> Where one of the flags is VRING_DESC_INDIRECT, which means that the 
>> memory within (address, length) is a bunch of descriptors instead of raw 
>> data.
>>     
>
> If that's all we wanted, it's fairly easy to do as a future extension
> even if we didn't change it today.  My concern was the allocation and
> management of those sg pages; hence my desire for a patch 8)
>   

Won't kmalloc()/kfree() suffice?  IMO the tradeoff (compared to chaining 
with its reduction in ring size, and handling ood) is positive.

I'll try a patch based on the next patchset.

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