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Date: Wed, 09 Feb 2011 05:21:23 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: [Qemu-devel] Re: [PATCH 3/4] qed: Report error for unsupported
	features
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To: Kevin Wolf <kwolf@redhat.com>
Cc: stefanha@gmail.com, qemu-devel@nongnu.org, lcapitulino@redhat.com

On 02/09/2011 04:32 AM, Kevin Wolf wrote:
> Instead of just returning -ENOTSUP, generate a more detailed error.
>
> Unfortunately we don't have a helpful text for features that we don't know yet,
> so just print the feature mask. It might be useful at least if someone asks for
> help.
>
> Signed-off-by: Kevin Wolf<kwolf@redhat.com>
>    

We can use a compatible feature to create a feature name table.

> ---
>   block/qed.c |    8 +++++++-
>   1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/block/qed.c b/block/qed.c
> index 3273448..8b0a975 100644
> --- a/block/qed.c
> +++ b/block/qed.c
> @@ -14,6 +14,7 @@
>
>   #include "trace.h"
>   #include "qed.h"
> +#include "qerror.h"
>
>   static void qed_aio_cancel(BlockDriverAIOCB *blockacb)
>   {
> @@ -311,7 +312,12 @@ static int bdrv_qed_open(BlockDriverState *bs, int flags)
>           return -EINVAL;
>       }
>       if (s->header.features&  ~QED_FEATURE_MASK) {
> -        return -ENOTSUP; /* image uses unsupported feature bits */
> +        /* image uses unsupported feature bits */
> +        char version[64];
> +        snprintf(version, sizeof(version), "%" PRIx64, s->header.features);
>    

It would be useful to do s->header.features & QED_FEATURE_MASK here as a 
management tool doesn't know what features this version of QED supports.

Regards,

Anthony Liguori

> +        qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE,
> +            bs->device_name, version);
> +        return -ENOTSUP;
>       }
>       if (!qed_is_cluster_size_valid(s->header.cluster_size)) {
>           return -EINVAL;
>