Re: [Qemu-devel] Should we auto-generate IDs?

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

On Thu, Aug 27, 2015 at 11:22:58AM -0400, Programmingkid wrote:
> 
> On Aug 27, 2015, at 11:19 AM, Daniel P. Berrange wrote:
> 
> > On Thu, Aug 27, 2015 at 11:13:25AM -0400, Programmingkid wrote:
> >>> 
> >>>> What is wrong with having a predictable ID?
> >>>> 
> >>> 
> >>> As Daniel and Eric have noted, it could be nice to have a predictable
> >>> ID.  My concern with a predictable ID is that it creates, across
> >>> multiple sub-systems, an ABI that we will then need to make sure
> >>> always works.
> >>> 
> >>> For instance, I don't want management software or a user to rely on us
> >>> parsing devices, or image filenames / block driver states in a certain
> >>> order, and then anticipate the ID name.  I am concerned about creating
> >>> an interface that may inadvertently "break" later on, and imposing a
> >>> burden on QEMU that isn't reasonable.  Perhaps it is enough to just
> >>> rely on documentation for this, without enforcing it in the scheme.
> >> 
> >> If we do nothing, QEMU stays broken. The monitor command device_del
> >> and others that need an ID will not work still. Hopefully any changes we
> >> make to QEMU will be robust enough stand the test of time.
> > 
> > That is not correct. It is possible for us to fix object_del / device_del
> > to accept the QOM object path. It isn't pretty but it is a solution that
> > gives everything a stable unique path ID to use for deletion even if the
> > user forgets to give a pretty path-less ID.
> 
> This QOM path might be better than nothing. Hopefully someone will make this
> patch and share it with us.

I sent a patch to support that, since it turned out to be pretty
trivial to implement. So that at least solves the immediate blocking
issue of deleting devices with an ID. The question of usability and
auto-generated IDs can continue in parallel....

Regards,
Daniel
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