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Date: Thu, 03 Feb 2011 10:39:40 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH 01/20] qdev: add print_options callback
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To: Alon Levy <alevy@redhat.com>
Cc: qemu-devel@nongnu.org

On 02/02/2011 02:28 PM, Alon Levy wrote:
> another callback added to PropertyInfo, for later use by PROP_TYPE_ENUM.
> Allows printing of runtime computed options when doing:
>   qemu -device foo,?
> ---
>   hw/qdev.c |   10 +++++++++-
>   hw/qdev.h |    1 +
>   2 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/hw/qdev.c b/hw/qdev.c
> index c7fec44..0b2ad3d 100644
> --- a/hw/qdev.c
> +++ b/hw/qdev.c
> @@ -187,7 +187,15 @@ int qdev_device_help(QemuOpts *opts)
>           if (!prop->info->parse) {
>               continue;           /* no way to set it, don't show */
>           }
> -        error_printf("%s.%s=%s\n", info->name, prop->name, prop->info->name);
> +        if (prop->info->print_options) {
> +            char buf[256];
> +            int ret;
> +            ret = prop->info->print_options(info, prop, buf, sizeof(buf) - 3);
> +            error_printf("%s.%s=%s%s\n", info->name, prop->name, buf,
> +                ret == sizeof(buf) - 3 ? "..." : "" );
> +        } else {
> +            error_printf("%s.%s=%s\n", info->name, prop->name, prop->info->name);
> +        }
>       }
>       return 1;
>   }
> diff --git a/hw/qdev.h b/hw/qdev.h
> index 9808f85..fa3221b 100644
> --- a/hw/qdev.h
> +++ b/hw/qdev.h
> @@ -109,6 +109,7 @@ struct PropertyInfo {
>       enum PropertyType type;
>       int (*parse)(DeviceState *dev, Property *prop, const char *str);
>       int (*print)(DeviceState *dev, Property *prop, char *dest, size_t len);
> +    int (*print_options)(DeviceInfo *info, Property *prop, char *dest, size_t len);
>    

I'm not clear what the different between print and print_options is and 
why two callbacks are needed.  Can you explain and comments to the patch 
clarifying why two interfaces are needed.  Even better would be if one 
interface could handle it.

Regards,

Anthony Liguori


>       void (*free)(DeviceState *dev, Property *prop);
>   };
>
>