On Thu, Nov 21, 2024 at 06:29:06PM +0100, Philippe Mathieu-Daudé wrote:
> On 21/11/24 18:17, Peter Xu wrote:
> > On Thu, Nov 21, 2024 at 02:01:45PM +0100, Philippe Mathieu-Daudé wrote:
> > > On 21/11/24 11:30, Daniel P. Berrangé wrote:
> > > > On Wed, Nov 20, 2024 at 04:57:01PM -0500, Peter Xu wrote:
> > > > > Always explicitly create QEMU system containers upfront.
> > > > >
> > > > > Root containers will be created when trying to fetch the root object
> > > > > the
> > > > > 1st time. Machine sub-containers will be created only until machine
> > > > > is
> > > > > being initialized.
> > > > >
> > > > > Signed-off-by: Peter Xu <pet...@redhat.com>
> > > > > ---
> > > > > hw/core/machine.c | 19 ++++++++++++++++---
> > > > > qom/object.c | 16 +++++++++++++++-
> > > > > 2 files changed, 31 insertions(+), 4 deletions(-)
> > > >
> > > >
> > > > > diff --git a/qom/object.c b/qom/object.c
> > > > > index 214d6eb4c1..810e6f2bd9 100644
> > > > > --- a/qom/object.c
> > > > > +++ b/qom/object.c
> > > > > @@ -1734,12 +1734,26 @@ const char *object_property_get_type(Object
> > > > > *obj, const char *name, Error **errp
> > > > > return prop->type;
> > > > > }
> > > > > +static Object *object_root_initialize(void)
> > > > > +{
> > > > > + Object *root = object_new(TYPE_CONTAINER);
> > > > > +
> > > > > + /*
> > > > > + * Create all QEMU system containers. "machine" and its
> > > > > sub-containers
> > > > > + * are only created when machine initializes
> > > > > (qemu_create_machine()).
> > > > > + */
> > > > > + container_create(root, "chardevs");
> > > > > + container_create(root, "objects");
> > > >
> > > > This is where I would expect 'backend' to have been created
> > > > rather than ui/console.c, though you could potentially make
> > > > a case to create it from the machine function, snice console
> > > > stuff can't be used outside of the machine context, while
> > > > chardevs/objects can be used in qemu-img/qemu-nbd, etc
> >
> > Would it hurt if we do it altogether here even if it won't be used in
> > qemu-img/qemu-nbd?
> >
> > IMHO we should either make it simple (assuming empty containers won't hurt
> > there..), or we should just leave "backend" to ui/ code, so we don't assume
> > which binary is using the ui code: whoever uses it will create the
> > container.
> >
> > >
> > > What about creating "backend" container in qemu_create_machine()?
> >
> > I remember I started with that but it didn't work. IIRC that's because
> > machine_initfn() (or somewhere around the init code) requires the
> > containers to present, hence it's too late even if we create the containers
> > right after this line:
> >
> > current_machine =
> > MACHINE(object_new_with_class(OBJECT_CLASS(machine_class)));
>
> So qemu_create_machine_containers() really belongs to qemu_create_machine()
> =)
Frankly, I don't immediately get this line..
But when I was trying again just to check my memory, I can't see anything
crash anymore, moving things over.
So while I'll test some more, I can switch to that if I cannot reproduce
any issue with it. That's:
===8<===
diff --git a/hw/core/machine.c b/hw/core/machine.c
index ed613ec4cb..a72c001c3d 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -1193,27 +1193,11 @@ static void machine_class_base_init(ObjectClass *oc,
void *data)
}
}
-static const char *const machine_containers[] = {
- "unattached",
- "peripheral",
- "peripheral-anon"
-};
-
-static void qemu_create_machine_containers(Object *machine)
-{
- int i;
-
- for (i = 0; i < ARRAY_SIZE(machine_containers); i++) {
- object_property_add_new_container(machine, machine_containers[i]);
- }
-}
-
static void machine_initfn(Object *obj)
{
MachineState *ms = MACHINE(obj);
MachineClass *mc = MACHINE_GET_CLASS(obj);
- qemu_create_machine_containers(obj);
ms->dump_guest_core = true;
ms->mem_merge = (QEMU_MADV_MERGEABLE != QEMU_MADV_INVALID);
ms->enable_graphics = true;
diff --git a/system/vl.c b/system/vl.c
index 822f7ff656..cdc0b6e10c 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -2112,6 +2112,21 @@ static void parse_memory_options(void)
loc_pop(&loc);
}
+static const char *const machine_containers[] = {
+ "unattached",
+ "peripheral",
+ "peripheral-anon"
+};
+
+static void qemu_create_machine_containers(Object *machine)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(machine_containers); i++) {
+ object_property_add_new_container(machine, machine_containers[i]);
+ }
+}
+
static void qemu_create_machine(QDict *qdict)
{
MachineClass *machine_class = select_machine(qdict, &error_fatal);
@@ -2120,6 +2135,7 @@ static void qemu_create_machine(QDict *qdict)
current_machine =
MACHINE(object_new_with_class(OBJECT_CLASS(machine_class)));
object_property_add_child(object_get_root(), "machine",
OBJECT(current_machine));
+ qemu_create_machine_containers(OBJECT(current_machine));
object_property_add_child(machine_get_container("unattached"),
"sysbus", OBJECT(sysbus_get_default()));
--
Peter Xu
