On Thu, May 14, 2026 at 8:47 PM Stefan Hajnoczi <[email protected]> wrote:
>
> On Sun, May 10, 2026 at 07:50:56PM +0200, Sam Li wrote:
> > Add the specs for the zoned format feature of the qcow2 driver.
> > The qcow2 file then can emulate real zoned devices, either passed
> > through by virtio-blk device or NVMe ZNS drive to the guest
> > given zoned information.
> >
> > Signed-off-by: Sam Li <[email protected]>
> > Reviewed-by: Stefan Hajnoczi <[email protected]>
> > ---
> >  docs/system/qemu-block-drivers.rst.inc | 42 ++++++++++++++++++++++++++
> >  1 file changed, 42 insertions(+)

Hi Stefan,

Thanks for reviewing!

> >
> > diff --git a/docs/system/qemu-block-drivers.rst.inc 
> > b/docs/system/qemu-block-drivers.rst.inc
> > index 384e95ba76..5066c943d5 100644
> > --- a/docs/system/qemu-block-drivers.rst.inc
> > +++ b/docs/system/qemu-block-drivers.rst.inc
> > @@ -172,6 +172,48 @@ 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:: zone.mode
> > +    If this is set to ``host-managed``, the image is an emulated zoned
> > +    block device. This option is only valid to emulated zoned device files.
> > +
> > +  .. option:: zone.size
> > +
> > +    The size of a zone in bytes. The device is divided into zones of this
> > +    size with the exception of the last zone, which may be smaller.
>
> This option is required when zone.mode=host-managed?
>
> It would be useful to indicate whether each option listed here is
> required or has a default value when absent.

Makes sense. I'll set the default to 256MB.

>
> > +
> > +  .. option:: zone.capacity
> > +
> > +    The initial capacity value, in bytes, 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 zone capacity is per zone and may be different between zones in 
> > real
> > +    devices. QCow2 sets all zones to the same capacity.
>
> This defaults to zone.size?

Yes.

>
> > +
> > +  .. option:: zone.conventional_zones
> > +
> > +    The number of conventional zones of the zoned device.
>
> This defaults to (size + size.size - 1) / zone.size?

Or just zero, meaning all zones are sequential write required.

>
> > +
> > +  .. option:: zone.max_active_zones
> > +
> > +    The limit of the zones with implicit open, explicit open or closed 
> > state.
> > +
> > +    The max active zones must be less or equal to the number of SWR
> > +    (sequential write required) zones of the device.
>
> This defaults to (size + size.size - 1) / zone.size?

Or maybe zero, meaning no limit. Although it does have a limit lower
than nr_zones.

>
> > +
> > +  .. option:: zone.max_open_zones
> > +
> > +    The maximal allowed open zones. The max open zones must not be larger 
> > than
> > +    the max active zones.
> > +
> > +    If the limits of open zones or active zones are equal to the number of
> > +    SWR zones, then it is the same as having no limits.
>
> This defaults to max_active_zones?

Yes, if max_active_zone is set, otherwise zero.

>
> > +  .. option:: zone.max_append_bytes
> > +
> > +    The number of bytes in a zone append request that can be issued to the
> > +    device. It must be 512-byte aligned and less than the zone capacity.
>
> Is there a default?

Yes, it can set to 64 KB.

>
> > +
> >  .. program:: image-formats
> >  .. option:: qed
> >
> > --
> > 2.43.0
> >

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