[libvirt] [PATCHv4 0/3] Add support for file memorybacking

[Michal Privoznik]

On 13.12.2016 13:12, Jaroslav Safka wrote:
> Hi,
> we would like to introduce 3 new elements source,access and allocation in memoryBacking element.
> For now it was made for numa topology.
> 
> <memoryBacking>
>      <source type="file|anonymous"/>
>      <access mode="shared|private"/>
>      <allocation mode="immediate|ondemand"/>
> </memoryBacking>
> 
> If allocation is immediate then -mem-prealloc should be added to the qemu commanline.
> If source is file then
> -object memory-backend-file,id=mem,size=1024M,mem-path=*lib dir path* -numa node,memdev=mem Will be added to the qemu commandline
> 
> If access is shared then the "share=on" parameter will be added to the memory-backend-file e.g.
> -object memory-backend-file,id=mem,size=1024M,mem-path=/var/lib/libvirt/qemu,share=on
> 
> The access mode can be overriden by specifying token memAccess in numa cell.
> 
> The test cpu-numa-memshared was removed, because behaviour was changed and is not needed anymore

I beg to disagree. What if you don't have any <memoryBacking/>?

I like these patches, but I'm not certainly sure about:
a) domain XML (in the past we used to require an ACK on schema change
from one of the Dans)
b) the location for qemu to create its mmaped files (patch 3/3).
cfg->libDir looks very suspicious.

I have the patches applied locally with all the changes I've pointed out
applied. If we have answers to both of the questions, I can push these.

Michal