Re: [Qemu-devel] Feature request: integrated smb server?

[David E . Still]

> On Thu, 2004-09-02 at 16:21, David E.Still wrote:
> > what would it take to integrate a small smb server intoqemu's
> > networking code?
>
> A lot. Having implemented a NetBT stack and read a lot about SMB in a
> past life, there's no such thing as a small SMB server; it's a complex
> layered set of protocols. You would have to integrate Samba if you
> really wanted to do this feasibly.

I kind of figured this might be the case, but I thought it wouldn't 
hurt to ask. :)

> Curious, what is your need? As you say, most OS's can mount and expose
> SMB shares. That means that the guest can already do what you want. Why
> not just expose an SMB share in the guest and mount it over the 
> network?
> VmWare's integrated SMB server is one of the bits of evil in it; I've
> had issues with VmWare's various services that it installs interfering
> with the real thing...

My "need" is for the guest OS to be able to read/write files in a 
folder on the host OS.  FTP can do it, but smb would be "easier" in the 
sense that the guest would see it as just another mounted disk.

> The argument you could make for such a feature is zero setup to do. 
> Just
> start the guest, and QEMU exposes the file transfer service. The guest
> doesn't know anything about it. The user doesn't have to set anything
> up.

Yes, it's largely an ease-of-use issue.  I run QEMU on Mac OS X and 
Mandrake 10.0 (x86), but I have yet to be able to successfully 
configure a tun/tap network connection, which would probably allow me 
to use a smb share between the host and guest.  I've tried on and off 
ever since I discovered bochs a couple of years ago, but I could never 
quite get it to work.  User networking in QEMU is just so much easier.  
I'm spoiled! :)

> > beable to write and *install* to the host system.  I'm not suggesting
>
> What do you mean by install? Don't installers usually have to access 
> the
> registry?

As I said, I run Mandrake 10.0 on my home computer.  I haven't had any 
Windows partitions for years, but I still like to fire up an 
occassional game using using WINE (either plain or Transgaming's 
Cedega/WineX).  I've discovered that some games will run fine, but have 
great difficulty with the installation process.  If I can install the 
the SMB share by running Win98 in QEMU, then I can attempt to run the 
binary installation using WINE.  FTP over QEMU's networking tends to be 
rather slow (I've done it using non-host computer on the LAN).  I 
completely understand that software installed on a virtual machine 
won't completely install on the host (i.e., with registry settings, 
etc.).

> There was a thread a little while back that discusses your suggestion.
> Fabrice decided that FTP was the way to go over HTTP or SMB, since it 
> is
> simple and clients are readily available. One thing to understand is
> that the last mile to the guest's disk is a tricky thing. Operating
> systems tend to make the assumption that they have exclusive access to
> filesystems they have mounted. So read-only access is probably the best
> you can hope for without living very dangerously.
>
> On Windows, if you really want to be able to write to the host file
> system, you should probably go through SMB to do it. Then all the
> authentication, arbitration, perimissions, decryption, etc. is done by
> the host OS. And if you believe that, then you have to set up an SMB
> client to talk to Window's SMB server anyway. So embedding an SMB 
> server
> wouldn't save any work.

Embedding an SMB server would save the need for a tun/tap connection, 
which, historically, has been the bane of my virtual networking 
existence. :P  User networking in QEMU has always "just worked."  
(Yeah, I'm getting spoiled by my Mac. ;) )

> Of course there could be simplifying assumptions I'm missing that could
> take SMB out of the equation. I'm interested to hear those from
> others...
>
> -- John.

If the cost (in this case development time) greatly outweighs the 
benefits (easy file sharing between guest and host), then I can 
certainly accept that.

- Stealth Dave