On 12/16/2011 04:05 PM, Anthony Liguori wrote:
What are the uses of null in qdev string properties? I know you can't
set a string to null since parse() doesn't have a null syntax. So we're
really just talking about an uninitialized state, right?
Yes. No ROM BAR is an example of a NULL string property.
So it's really filenames and backend names, right? Can we just treat
empty strings like NULL? I think all of the various bits handles both
the same way.
The only case I can think of when it differs is serial numbers. An
empty serial number is different from no serial number (which means do
not expose one at all).
However, DEFINE_PROP_STRING does not allow setting a default, and some
device models rely on a NULL value as a default. I see two ways out: 1)
add nullable strings; 2) merge without this patch, knowing qom-get is
kind-of broken, and proceed adding a default to all DEFINE_PROP_STRING;
this would be a merge nightmare for you. 3) merge without this patch,
knowing it's kind-of broken, and later decide what to do.
Let's do (3), and add nullable strings if the discussion stalls.
Paolo
