On Thu, Dec 03, 2015 at 05:37:39PM +0100, Markus Armbruster wrote:
> prop_get_fdt() misuses the visitor API: when fdt is null, it doesn't
> visit anything. object_property_get_qobject() happily
> object_property_get_qobject(). Amazingly, the latter survives the
> misuse. Turns out we've papered over it long before prop_get_fdt()
> existed, in commit 1d10b44.
>
> However, commit 6c2f9a1 changed how we paper over it, and as a side
> effect changed qom-get's value from {} to null. Change it right back
> by fixing the visitor misuse.
>
> Signed-off-by: Markus Armbruster <arm...@redhat.com>
> ---
> hw/ppc/spapr_drc.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
> index 4e7a1d3..dad157f 100644
> --- a/hw/ppc/spapr_drc.c
> +++ b/hw/ppc/spapr_drc.c
> @@ -259,6 +259,11 @@ static void prop_get_fdt(Object *obj, Visitor *v, void
> *opaque,
> void *fdt;
>
> if (!drc->fdt) {
> + visit_start_struct(v, NULL, NULL, name, 0, &err);
> + if (!err) {
> + visit_end_struct(v, &err);
> + }
> + error_propagate(errp, err);
> return;
> }
>
I'm not entirely convinced by this. IIUC, this makes the output in
the case of NULL (i.e. missing) fdt identical to the output in the
case of an empty, valid fdt - in dtc syntax, this:
/ {
};
Those are different cases from the point of view of the code which
actually uses the fdt, and for purposes of debugging it, I suspect we
want to expose that difference.
I don't know what the QOMishly correct way of doing that is, though.
Can we somehow make the "fdt" property disappear entirely if fdt is
NULL?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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