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Date: Wed, 11 Jul 2012 11:03:19 -0300
From: Luiz Capitulino <lcapitulino@redhat.com>
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Subject: Re: [Qemu-devel] [v1 Patch 1/10]Qemu: Enhance "info block" to
 display host cache setting
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Supriya Kannery <supriyak@linux.vnet.ibm.com>, Shrinidhi Joshi <spjoshi31@gmail.com>, Stefan Hajnoczi <stefanha@gmail.com>, Jeff Cody <jcody@redhat.com>, qemu-devel@nongnu.org, Eric Blake <eblake@redhat.com>, Christoph Hellwig <hch@lst.de>

On Mon, 09 Jul 2012 16:43:40 +0200
Kevin Wolf <kwolf@redhat.com> wrote:

> Am 15.06.2012 23:07, schrieb Eric Blake:
> > On 06/15/2012 02:47 PM, Supriya Kannery wrote:
> >> Enhance "info block" to display hostcache setting for each
> >> block device.
> >>
> > 
> >>  ##
> >>  { 'type': 'BlockInfo',
> >>    'data': {'device': 'str', 'type': 'str', 'removable': 'bool',
> >> -           'locked': 'bool', '*inserted': 'BlockDeviceInfo',
> >> +           'locked': 'bool','hostcache': 'bool', '*inserted': 'BlockDeviceInfo',
> > 
> > space after comma
> > 
> > Since 'hostcache' was not present when talking to older qemu, should we
> > mark it optional?
> 
> What does "optional" really mean? I always understood that it means that
> whether the field exists or not depends on some runtime condition, not
> on the qemu version. I would specify something like this, that always
> exists in new qemu versions, in the "Since" section. Or maybe a separate
> "Since" specification like in SpiceInfo for mouse-mode.

Yes, Kevin is right.