Re: [Virtio-fs] virtio-fs on zLinux (s390x)

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Gong Su (gongsu@us.ibm.com) wrote:
> 
> 
> Hi Stefan, I'm resending my questions to the list per your request.
> 
> Basically, I'm trying to see if I can get virtio-fs to work on zLinux.
> Following the instructions on https://virtio-fs.gitlab.io/howto-qemu.html I
> was able to compile all the pieces but when I tried to run qemu I realized
> that it needs -numa option which isn't supported on s390x yet.
> 
> I have talked to Christian Borntraeger (whom I worked with on other
> projects before) and he indicated that he had a plan to add -numa support
> for s390x but currently is busy on other things.
> 
> So I'm trying to see if there are other ways for me to go forward without
> having to wait for Christian. I see two options:
> 
> 1. Merge virtiofsd into qemu itself. In the "Interchangeability" section of
> the virtio-fs design page (https://virtio-fs.gitlab.io/design.html), it
> mentioned that "It is also possible to forego vhost-user and emulate the
> virtio-fs device directly inside the hypervisor, although this may result
> in poor isolation and security." Since each guest typically gets its own
> qemu process, maybe this is acceptable for some use cases. In exchange, you
> get the benefit of not having to carve out a chunk of memory from /dev/shm
> (and maybe simpler communication between virtiofsd and qemu).
> 2. Use something other than -numa to share memory between virtiofsd and
> qemu that's supported on zLinux. I'm not entirely familiar with qemu so I
> have no idea whether this is possible or not.

Hi,
  My understanding is that Igor Mammedov (imammedo@redhat.com) has plans
to allow 'shared' to be set on main memory, so we wouldn't need the numa
code.

Dave

> Thanks.

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--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK