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Date: Thu, 4 Aug 2011 09:31:57 +0100
Message-ID: <CAJSP0QX2gTXYSgSmt0ZYsCDm_DL-V0MCCmp1vnDjTetpZbmrJQ@mail.gmail.com>
From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [V5 Patch 3/4]Qemu: Command "block_set" for
 dynamic block params change
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To: supriyak@linux.vnet.ibm.com
Cc: Kevin Wolf <kwolf@redhat.com>, Christoph Hellwig <hch@lst.de>, qemu-devel@nongnu.org

On Thu, Aug 4, 2011 at 9:32 AM, Supriya Kannery
<supriyak@linux.vnet.ibm.com> wrote:
> On 08/01/2011 09:14 PM, Anthony Liguori wrote:
>>
>> On 08/01/2011 10:44 AM, Kevin Wolf wrote:
>>>
>>> Am 01.08.2011 17:28, schrieb Anthony Liguori:
>>>>>
>>>>> 2. Top-level command for each parameter (e.g. block_set_hostcache).
>>>>> Supported parameters are easily discoverable via query-commands. If
>>>>> individual block devices support different sets of parameters then
>>>>> they may have to return -ENOTSUPP.
>>>>>
>>>>> I like the block_set approach.
>>>>>
>>>>> Anthony, Kevin, Supriya: Any thoughts?
>>>>
>>>> For the sake of overall QMP sanity, I think block_set_hostcache is
>>>> really our only option.
>>>
>>> Ideally we should have blockdev_add, and blockdev_set would just take
>>> the same arguments and update the given driver.
>>
>> Ideally we'd have a backend_add, backend_set, etc.
>>
>> But in the absence of that, we should provide the best interface we can
>> with the current tools we have.
>>
>> For now, using high level commands is the best we can do.
>
> Will be modifying code to have 'block_set_hostcache' command implemented.
> Along with that, planning to implement 'query-block_set_hostcache', that
> returns current hostcache setting
> for all the applicable block devices.

I don't think a query command is necessary since query-block already
reports this information.

Stefan