Re: [Xen-devel] tapdisk in debian 3.11 kernel

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 3 Jan 2014, James Harper wrote:
> > > and get rbd with ceph under hvm. Probably pv too but I can't seem to get
> > > an 'xl console' working to check right now.
> > 
> > Nice! Please send the libxl patches to the list!
> > 
> > The reason why libxl has a specific list of supported formats is that we
> > thought that a simple wildcard and external bash scripts without a clear
> > calling convention were too fragile. Of course if RDB "just works", we
> > should enable it in libxl.

Sorry, I realize now that the word "format" in my reply is wrong.  I
should have written "targets", like iscsi and nfs, each of them can
support multiple image formats like raw and qcow2.


> It turns out that simply omitting the format altogether is sufficient, and 
> probably preferable. Something like:
> 
> disk = [ 'rbd:prod/virt-zoneminder-root,,xvda1,rw,backendtype=qdisk' ]
> 
> seems to work fine on a standard Debian system with only qemu recompiled with 
> rbd enabled (my test system has probably suffered a bit of bitrot and so 
> couldn't really be called standard, but I did just reinstall the 
> xen-utils-4.3 package that contains libxl so it should be back to defaults)
> 
> I can probably still put a patch together but I think a better thought out 
> "if backendtype=qdisk then don't check the format" would be better, unless it 
> opens up a security hole or something.

Unfortunately it does, in fact we turn off automatic format recognition
in QEMU on purpose. But in this case, shouldn't:

disk = [ 'rbd:prod/virt-zoneminder-root,raw,xvda1,rw,backendtype=qdisk' ]

just work?

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