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Date: Fri, 29 Aug 2014 08:55:00 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v3] block: Introduce "null" driver
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To: Eric Blake <eblake@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, benoit.canet@irqsave.net, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, armbru@redhat.com

On Thu, 08/28 16:23, Eric Blake wrote:
> On 08/27/2014 11:53 PM, Fam Zheng wrote:
> > This is an analogue to Linux null_blk. It can be used for testing block
> > device emulation and general block layer functionalities such as
> > coroutines and throttling, where disk IO is not necessary or wanted.
> > 
> > Use null:// for AIO version, and null-co:// for coroutine version.
> > 
> > Signed-off-by: Fam Zheng <famz@redhat.com>
> > 
> > ---
> 
> > +++ b/qapi/block-core.json
> > @@ -1150,7 +1150,8 @@
> >    'data': [ 'archipelago', 'file', 'host_device', 'host_cdrom', 'host_floppy',
> >              'http', 'https', 'ftp', 'ftps', 'tftp', 'vvfat', 'blkdebug',
> >              'blkverify', 'bochs', 'cloop', 'cow', 'dmg', 'parallels', 'qcow',
> > -            'qcow2', 'qed', 'raw', 'vdi', 'vhdx', 'vmdk', 'vpc', 'quorum' ] }
> > +            'qcow2', 'qed', 'raw', 'vdi', 'vhdx', 'vmdk', 'vpc', 'quorum',
> > +            'null' ] }
> 
> As mentioned elsewhere, you probably want 'null' AND 'null-co'.  Bummer
> that this list is mostly alphabetical, but that 'quorum' and 'null' are
> out of order.

I'll add null-co to the list. But this list is a bit far from alphabetical:

archipelago, ..., vvfat, blkdebug,...

> 
> >  
> >  ##
> >  # @BlockdevOptionsBase
> > @@ -1203,6 +1204,19 @@
> >    'data': { 'filename': 'str' } }
> >  
> >  ##
> > +# @BlockdevOptionsNull
> > +#
> > +# Driver specific block device options for the null backend.
> > +#
> > +# @size:    size of the device in bytes.
> 
> missing an #optional marker

Will add.

Thanks,
Fam