Re: [Qemu-devel] [PATCH] Revert "virtio_rng: replace custom backend API with UserCreatable.complete() callback"

[Amos Kong]

On Tue, Aug 19, 2014 at 03:47:20PM +0100, Stefan Hajnoczi wrote:
> On Sat, Aug 16, 2014 at 12:23:52AM +0800, Amos Kong wrote:
> > This reverts commit 57d3e1b3f52d07d215ed96df946ee01f8d9f9526.
> > 
> > The commit introduced a regression bug, the initialization order of 
> > virtio-rng
> > backend was changed.
> > 
> >  # x86_64-softmmu/qemu-system-x86_64 -monitor stdio -vnc :0 \
> >      -chardev socket,host=localhost,port=1024,id=chr0 \
> >      -object rng-egd,chardev=chr0,id=rng0


Paolo posted a new patch [1] to fix this bug, above commandline works.

> >  qemu-system-x86_64: -object rng-egd,chardev=chr0,id=rng0: Device 'chr0' 
> > not found
> > 
> > Chardev 'chr0' isn't initialized when we try to open rng backend,
> 
> More detail:
> The problem is that vl.c:main() calls object_create() on -object before
> -chardev options are processed.  Moving the object_create() call after
> chardev is arbitrary and does not work if a chardev depends on an
> -object.

Stefan, can you give an example of the complex relying? So Paolo's patch can't
solve this problem?
 
> It would have been nice to process command-line options in left-to-right
> order instead of grouping them by option type.  I doubt we can change
> this now since it would break the command-line.
> 
> > Conflicts:
> >     hw/virtio/virtio-rng.c
> 
> This shouldn't be here.
> 
> I agree with reverting commit 57d3e1b3f52d07d215ed96df946ee01f8d9f9526.



-- 
                        Amos.

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