Re: [Qemu-devel] [PATCH 2/3] qdev: Add help for property value

[Markus Armbruster]

Stefan Weil <address@hidden> writes:

> When called with property value "?",
> a help text will be printed (instead of an error message).
>
> This is useful for command lines like
>       qemu -device e1000,mac=?
> and is already standard for other command line options.
>
> A better help text could be provided by extending
> the Property structure with a desc field.
>
> Signed-off-by: Stefan Weil <address@hidden>
> ---
>  hw/qdev-properties.c |    9 +++++++--
>  1 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
> index 8547ad2..f5ca05f 100644
> --- a/hw/qdev-properties.c
> +++ b/hw/qdev-properties.c
> @@ -565,8 +565,13 @@ int qdev_prop_parse(DeviceState *dev, const char *name, 
> const char *value)
>          return -1;
>      }
>      if (prop->info->parse(dev, prop, value) != 0) {
> -        fprintf(stderr, "property \"%s.%s\": failed to parse \"%s\"\n",
> -                dev->info->name, name, value);
> +        if (strcmp(value, "?") != 0) {
> +            fprintf(stderr, "property \"%s.%s\": failed to parse \"%s\"\n",
> +                    dev->info->name, name, value);
> +        } else {
> +            fprintf(stderr, "%s.%s=%s\n",
> +                    dev->info->name, name, prop->info->name);
> +        }
>          return -1;
>      }
>      return 0;

This one is problematic.  If prop->info->parse() accepts "?", help is
inaccessible.  PATCH 1/3 is immune to that problem, because we won't
name a property "?".

PATCH 1/3 already makes -device FOO,? print all property names.  I
figure it could just as well print all help along with names.