Re: [Xen-devel] [Qemu-devel] [PATCH v3 2/4] GlobalProperty: Display warning about unused -global

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 04/18/14 11:21, Andreas Färber wrote:
> Hi Don,
>
> Am 25.03.2014 00:55, schrieb Don Slutz:
> > This can help a user understand why -global was ignored.
> >
> > For example: with "-vga cirrus"; "-global vga.vgamem_mb=16" is just
> > ignored when "-global cirrus-vga.vgamem_mb=16" is not.
> >
> > This is currently clear when the wrong property is provided:
> >
> > out/x86_64-softmmu/qemu-system-x86_64 -global cirrus-vga.vram_size_mb=16 
> > -monitor pty -vga cirrus
> > char device redirected to /dev/pts/20 (label compat_monitor0)
> > qemu-system-x86_64: Property '.vram_size_mb' not found
> > Aborted (core dumped)
> >
> > vs
> >
> > out/x86_64-softmmu/qemu-system-x86_64 -global vga.vram_size_mb=16 -monitor pty 
> > -vga cirrus
> > char device redirected to /dev/pts/20 (label compat_monitor0)
> > VNC server running on `::1:5900'
> > ^Cqemu: terminating on signal 2
> >
> > Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>
> Improving this is greatly appreciated, thanks.
>
> Now, I can see two ways things can go wrong: a) Mistyping or later
> refactoring devices, or b) user typos or thinkos.
> And four ways to set globals: -global, config file (I hope?), legacy
> command line options (vl.c) and machine .compat_props.
>
> If a property does not exist on the instance of an existing type,
> object_property_parse() will raise an Error and we will abort in
> device_post_init().
>
> What we are silently missing is if a type is misspelled; for that we can
> probably add an Error **errp to the two qdev_prop_register_global*()
> functions - assuming QOM types are already registered at that point.
> qom-test would help us catch any such mistake by instantiating each machine.
I assume you are talking about qdev_prop_register_global() and
qdev_prop_register_global_list().  In my testing I did not see
QOM types being registered at that point.  I may have not been
looking at the right thing.  What I am sure on is that the new
object pc-memory-layout (added in 2/4) is not there just like
TYPE_ICC_BRIDGE at the calls to qdev_prop_register_global*().

Currently I have issues running tests:

dcs-xen-50:~/qemu/out>make test
make -C tests/tcg test
make[1]: Entering directory `/home/don/qemu/out/tests/tcg'
cc -m32 -I/home/don/qemu/tcg -I/home/don/qemu/tcg/i386 
-I/home/don/qemu/linux-headers -I/home/don/qemu/out/linux-headers -I. 
-I/home/don/qemu -I/home/don/qemu/include -I/home/don/qemu/libcacard 
-I/home/don/qemu/tests/tcg -I. -I../.. -pthread -I/usr/include/glib-2.0 
-I/usr/lib64/glib-2.0/include -Wall -O2 -g -fno-strict-aliasing -c -o 
test_path.o /home/don/qemu/tests/tcg/test_path.c
In file included from /home/don/qemu/util/cutils.c:25:0,
                 from /home/don/qemu/tests/tcg/test_path.c:4:
/home/don/qemu/include/qemu/host-utils.h: In function 'mulu64':
/home/don/qemu/include/qemu/host-utils.h:35:5: error: unknown type name 
'__uint128_t'
/home/don/qemu/include/qemu/host-utils.h:35:22: error: '__uint128_t' undeclared 
(first use in this function)
/home/don/qemu/include/qemu/host-utils.h:35:22: note: each undeclared 
identifier is reported only once for each function it appears in
...




> I note that your proposed check is not failing, but still, with hot-add
> of e.g. PCI devices we might well get a global property default for a
> type that is not instantiated immediately but possibly used later on.
This looks correct to me.  I do not know enough in the area, but
at a quick look, type_register_static() could look at .hotpluggable
and .props.  and maybe do some checking.

> > ---
> >   hw/core/qdev-properties-system.c |  1 +
> >   hw/core/qdev-properties.c        | 15 +++++++++++++++
> >   include/hw/qdev-core.h           |  1 +
> >   include/hw/qdev-properties.h     |  1 +
> >   vl.c                             |  2 ++
> >   5 files changed, 20 insertions(+)
> FWIW I'd prefer "qdev:" for consistency (and yes, it's ambiguous), since
> there are no "GlobalProperty" files or directory.
Ok, Will change.

> > diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
> > index de83561..9c742ca 100644
> > --- a/hw/core/qdev-properties-system.c
> > +++ b/hw/core/qdev-properties-system.c
> > @@ -444,6 +444,7 @@ static int qdev_add_one_global(QemuOpts *opts, void *opaque)
> >       g->driver   = qemu_opt_get(opts, "driver");
> >       g->property = qemu_opt_get(opts, "property");
> >       g->value    = qemu_opt_get(opts, "value");
> > +    g->not_used = true;
> >       qdev_prop_register_global(g);
> >       return 0;
> >   }
> IIUC your patch relies on not_used being false in the non-QemuOpts case
> to avoid noise when using -nodefaults or pc*-x.y. Still, the C99 struct
> initializations elsewhere get that field as well, hmm. An alternative
> would be a separate linked list for user-supplied globals.
Yes, a separate linked list could be used.  Did not look at
doing this.  Mostly since struct init will always set not_used to false.


> > diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> > index c67acf5..437c008 100644
> > --- a/hw/core/qdev-properties.c
> > +++ b/hw/core/qdev-properties.c
> > @@ -951,6 +951,20 @@ void qdev_prop_register_global_list(GlobalProperty *props)
> >       }
> >   }
> >   
> > +void qdev_prop_check_global(void)
> > +{
> > +    GlobalProperty *prop;
> > +
> > +    QTAILQ_FOREACH(prop, &global_props, next) {
> > +        if (!prop->not_used) {
> > +            continue;
> > +        }
> > +        fprintf(stderr, "Warning: \"-global %s.%s=%s\" not used\n",
> > +                prop->driver, prop->property, prop->value);
> > +
> > +    }
> > +}
> > +
> >   void qdev_prop_set_globals_for_type(DeviceState *dev, const char *typename,
> >                                       Error **errp)
> >   {
> > @@ -962,6 +976,7 @@ void qdev_prop_set_globals_for_type(DeviceState *dev, const 
> > char *typename,
> >           if (strcmp(typename, prop->driver) != 0) {
> >               continue;
> >           }
> > +        prop->not_used = false;
> >           object_property_parse(OBJECT(dev), prop->value, prop->property, &err);
> >           if (err != NULL) {
> >               error_propagate(errp, err);
> > diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> > index dbe473c..131fb49 100644
> > --- a/include/hw/qdev-core.h
> > +++ b/include/hw/qdev-core.h
> > @@ -235,6 +235,7 @@ typedef struct GlobalProperty {
> >       const char *driver;
> >       const char *property;
> >       const char *value;
> > +    bool not_used;
> >       QTAILQ_ENTRY(GlobalProperty) next;
> >   } GlobalProperty;
> >   
> > diff --git a/include/hw/qdev-properties.h b/include/hw/qdev-properties.h
> > index c46e908..fbca313 100644
> > --- a/include/hw/qdev-properties.h
> > +++ b/include/hw/qdev-properties.h
> > @@ -180,6 +180,7 @@ void qdev_prop_set_ptr(DeviceState *dev, const char *name, 
> > void *value);
> >   
> >   void qdev_prop_register_global(GlobalProperty *prop);
> >   void qdev_prop_register_global_list(GlobalProperty *props);
> > +void qdev_prop_check_global(void);
> >   void qdev_prop_set_globals(DeviceState *dev, Error **errp);
> >   void qdev_prop_set_globals_for_type(DeviceState *dev, const char *typename,
> >                                       Error **errp);
> > diff --git a/vl.c b/vl.c
> > index acd97a8..61fac1b 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -4490,6 +4490,8 @@ int main(int argc, char **argv, char **envp)
> >           }
> >       }
> >   
> > +    qdev_prop_check_global();
> I have some doubts about this placement. A machine init done notifier
> might avoid touching vl.c by leaving it in qdev-properties.c. It happens
> to be after that point as is, but later refactorings wrt QOM realize or
> unrelated issues might change that.
Yes,  This was the best place I found for it.  I am happy to move
if that makes sense.

   -Don Slutz

> > +
> >       if (incoming) {
> >           Error *local_err = NULL;
> >           qemu_start_incoming_migration(incoming, &local_err);
> Regards,
> Andreas

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