Re: [RFC 1/4] docs/qcow2: add the zoned format feature

[Stefan Hajnoczi]

On Mon, Jun 05, 2023 at 06:41:05PM +0800, Sam Li wrote:
> Add the specs for the zoned format feature of the qcow2 driver. Once
> the zoned_profile is set to `zbc`, then the qcow2 file can be taken
> as zoned devices and passed through by virtio-blk device to the guest.
> 
> Signed-off-by: Sam Li <faithilikerun@gmail.com>
> ---
>  docs/system/qemu-block-drivers.rst.inc | 31 ++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/docs/system/qemu-block-drivers.rst.inc 
> b/docs/system/qemu-block-drivers.rst.inc
> index 105cb9679c..fdcf343652 100644
> --- a/docs/system/qemu-block-drivers.rst.inc
> +++ b/docs/system/qemu-block-drivers.rst.inc
> @@ -172,6 +172,37 @@ This section describes each format and the options that 
> are supported for it.
>      filename`` to check if the NOCOW flag is set or not (Capital 'C' is
>      NOCOW flag).
>  
> +  .. option:: zoned_profile
> +
> +    The option configures the zoned format feature on the qcow2 driver. If
> +    this is set to ``zbc``, then it follows the basics of ZBC/ZAC protocol.

What about virtio-blk? NVMe ZNS? Please indicate what effect the profile
has and whether it works with all emulated storage controllers that
support zoned storage.

> +
> +  .. option:: zone_size
> +
> +    The size of a zone of the zoned device. The zoned device have the same

"in bytes"? Please document the units.

> +    size of zones with an optional smaller last zone.

"The device is divided into zones of this size with the exception of the
last zone, which may be smaller."

> +
> +  .. option:: zone_capacity
> +
> +    The capacity of a zone of the zoned device.

This can be expanded:

  The initial capacity value for all zones. The capacity must be less
  than or equal to zone size. If the last zone is smaller, then its
  capacity is capped.

> The zoned device follows the
> +    ZBC protocol tends to have the same size as its zone.
> +
> +  .. option:: zone_nr_conv
> +
> +    The number of conventional zones of the zoned device.
> +
> +  .. option:: max_open_zones
> +
> +    The maximal allowed open zones.
> +
> +  .. option:: max_active_zones
> +
> +    The limit of the zones with implicit open, explicit open or closed state.
> +
> +  .. option:: max_append_sectors
> +
> +    The maximal sectors that is allowed to append to zones while writing.

Does "sectors" mean 512B blocks or logical block size?

> +
>  .. program:: image-formats
>  .. option:: qed
>  
> -- 
> 2.40.1
>

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