Re: [PATCH v4 11/42] virtio: add legacy feature table support

[Cornelia Huck]

On Tue, 25 Nov 2014 18:42:09 +0200
"Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:

> virtio blk has some legacy feature bits that modern drivers

virtio-blk

> must not negotiate, but are needed for old legacy hosts
> (e.g. that dn't support virtio scsi).

(that e.g. don't support virtio-scsi)

> Allow a separate legacy feature table for such cases.
> 
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
>  include/linux/virtio.h  |  4 ++++
>  drivers/virtio/virtio.c | 25 ++++++++++++++++++++++++-
>  2 files changed, 28 insertions(+), 1 deletion(-)
> 

> @@ -177,7 +185,22 @@ static int virtio_dev_probe(struct device *_d)
>  		driver_features |= (1ULL << f);
>  	}
> 
> -	dev->features = driver_features & device_features;
> +	/* Some drivers have a separate feature tables for virtio v1.0 */

/* some drivers have a separate feature table for legacy virtio */

?

> +	if (drv->feature_table_legacy) {
> +		driver_features_legacy = 0;
> +		for (i = 0; i < drv->feature_table_size_legacy; i++) {
> +			unsigned int f = drv->feature_table_legacy[i];
> +			BUG_ON(f >= 64);
> +			driver_features_legacy |= (1ULL << f);
> +		}
> +	} else {
> +		driver_features_legacy = driver_features;
> +	}
(...)

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/