Re: [Qemu-devel] [PATCH v5 02/18] block: add ability to set a prefix for opt names

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, Feb 23, 2017 at 11:28:39AM +0100, Kevin Wolf wrote:
> Am 22.02.2017 um 19:28 hat Eric Blake geschrieben:
> > Using '.' would mean a layer of {} nesting on the wire, maybe as in:
> > 
> > { "driver": "qcow2", ..., "luks" : { "hash-alg": ... } }
> > 
> > but conceptually, I like that a bit better, as it consolidates all the
> > luks-related options in one place, and may indeed make it possible to
> > reuse the type rather than having two variants (one prefixed, one not,
> > depending on whether it is standalone or qcow2).
> 
> Right, and this extra nesting to keep everything luks related in one
> place is exactly what I wanted to achieve with it.
> 
> > I'm also looking later in your series (13/18), where you have:
> > 
> > 
> > @@ -2344,7 +2348,8 @@
> >              '*l2-cache-size': 'int',
> >              '*refcount-cache-size': 'int',
> >              '*cache-clean-interval': 'int',
> > -            '*aes-key-secret': 'str' } }
> > +            '*aes-key-secret': 'str',
> > +            '*luks-key-secret': 'str' } }
> > 
> > 
> > Uggh - we have two optional parameters, that must not both be present at
> > once.  I'm wondering if we can instead do this (hmm, my patches for
> > anonymous base/branches in a flat union haven't been taken yet, but you
> > get the idea):
> > 
> > ...
> > '*cache-clean-interval': 'int',
> > '*encryption': 'Qcow2Encryption' } }
> > 
> > { 'enum': 'Qcow2EncryptionType': [ 'aes', 'luks' ] }
> > { 'union': 'Qcow2Encryption', 'base': { 'type': 'Qcow2EncryptionType' },
> >   'discriminator': 'type', 'data': {
> >     'aes': { 'key-secret': 'str' },
> >     'luks': { 'key-secret': 'str', '*hash-alg': ..., '*slot': 'int' } } }
> > 
> > so that you can only provide one encryption type, but once you have that
> > type, you can then provide all the associated fields for that type.  So
> > the QMP would look like:
> > 
> > { "driver": "qcow2", ..., "encryption" : { "type": "luks", "hash-alg":
> > ... } }
> 
> That's actually even better, a more accurate description of the options
> on the QAPI level. I like it.

Ok, I'll try implementing this approach, though I won't have time to do
this before soft-freeze, so the qcow2/luks feature is definitely 2.10
material now.

Regards,
Daniel
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