Re: [PATCH-for-6.2 v3 3/6] tests/unit/test-smp-parse: Explicit MachineClass name

[wangyanan (Y)]

On 2021/11/15 18:16, Philippe Mathieu-Daudé wrote:
> On 11/12/21 03:28, wangyanan (Y) wrote:
> > On 2021/11/11 18:03, Philippe Mathieu-Daudé wrote:
> > > If the MachineClass::name pointer is not explicitly set, it is NULL.
> > > Per the C standard, passing a NULL pointer to printf "%s" format is
> > > undefined. Some implementations display it as 'NULL', other as 'null'.
> > > Since we are comparing the formatted output, we need a stable value.
> > > The easiest is to explicit a machine name string.
> > >
> > > Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> > > ---
> > >    tests/unit/test-smp-parse.c | 8 ++++++--
> > >    1 file changed, 6 insertions(+), 2 deletions(-)
> > >    @@ -481,6 +483,8 @@ static void machine_class_init(ObjectClass *oc,
> > > void *data)
> > >          mc->smp_props.prefer_sockets = true;
> > >        mc->smp_props.dies_supported = false;
> > > +
> > > +    mc->name = g_strdup(SMP_MACHINE_NAME);
> > I'm not very familiar with Qom code, so it may be a stupid question.
> > The mc->name will be automatically freed elsewhere when all the
> > testing is finished and exits, right? :)
> I'll defer that to Eduardo / Markus, but meanwhile my understanding
> is QOM classes are loaded once (the first time an instance requires
> it) and never unloaded. Only instances can be unloaded, their resources
> being released.
Yes, this is also how I found about "classes" when reading the code and
playing with tests in test-smp-parse.c
> The machine life time is tied to the process one, when we are done
> using a machine, it is simpler to exit() the process -- the kernel
> releases the resources for us -- and create another process for a new
> machine, rather than re-creating a different machine within the same
> process.
> If there is a need for it (like releasing class resources), it is doable
> but it seems we never worried about it.
Ok, I see. Thank you for the explanations. :)

Thanks,
Yanan
> .