Re: [Qemu-devel] [GSoC 2010] Pass-through filesystem support.

[Jamie Lokier <jamie@shareable.org>]

Mohammed Gamal wrote:
> 2- With respect to CIFS. I wonder how the shares are supposed to be
> exposed to the guest. Should the Samba server be modified to be able
> to use unix domain sockets instead of TCP ports and then QEMU
> communicating on these sockets. With that approach, how should the
> guest be able to see the exposed share? And what is the problem of
> using Samba with TCP ports?

One problem with TCP ports is it only works when the guest's network
is up :) You can't boot from that.  It also makes things fragile or
difficult if the guest work you are doing involves fiddling with the
network settings.

Doing it over virtio-serial would have many benefits.

On the other hand, Samba+TCP+CIFS does have the advantage of working
with virtually all guest OSes, including Linux / BSDs / Windows /
MacOSX / Solaris etc.  9P only works with Linux as far as I know.

I big problem with Samba at the moment is it's not possible to
instantiate multiple instances of Samba any more, and not as a
non-root user.  That's because it contains some hard-coded paths to
directories of run-time state, at least on Debian/Ubuntu hosts where I
have tried and failed to use qemu's smb option, and there is no config
file option to disable that or even change all the paths.

Patching Samba to make per-user instantiations possible again would go
a long way to making it useful for filesystem passthrough.  Patching
it so you can turn off all the fancy features and have it _just_ serve
a filesystem with the most basic necessary authentication would be
even better.

-- Jamie