Re: [Qemu-devel] [RFC 3/7] block: bdrv_img_create(): move param printing to qemu-img

[Luiz Capitulino <lcapitulino@redhat.com>]

On Fri, 12 Oct 2012 10:29:37 +0200
Paolo Bonzini <pbonzini@redhat.com> wrote:

> Il 11/10/2012 23:27, Luiz Capitulino ha scritto:
> > bdrv_img_create() is being used by the transaction QMP command and
> > therefore shouldn't print directly to the user.
> > 
> > Move the param printing to qemu-img instead. Has the side effect of
> > only printing it when the bdrv_img_create() call succeeds, otherwise
> > we can print errors before the action being taken, eg:
> > 
> >    ~/work/virt/ ./qemu-img create -f qcow2 /foo/foo 10G
> >    qemu-img: /foo/foo: error while creating qcow2: No such file or directory
> >    Formatting '/foo/foo', fmt=qcow2 size=10737418240 encryption=off cluster_size=65536 lazy_refcounts=off
> 
> It is a small regression with -monitor stdio (and also with QMP it
> doesn't appear anymore in the logs).  Do we care? 

I don't think so. But if we do, than the current code is also wrong
as it should work with any -monitor device and not only stdio.

IMO, what's there today was really meant to be displayed when running
qemu-img.

> What alternatives
> exist besides writing a QAPI key-value store and converting the output
> QEMUOptionParameters to it (which I'm not suggesting to do)?

Yes, the right way to have this would be to add it as a return value
of the qmp command calling bdrv_img_create() (certainly not doable now
for the transaction command due to compatibility issues).

And/or add a query-block-image command and/or extend query-block to
display the image options...