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Re: [Qemu-devel] [PATCH v3] block: Introduce "null" driver
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v3] block: Introduce "null" driver |
Date: |
Thu, 28 Aug 2014 16:23:23 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 |
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 <address@hidden>
>
> ---
> +++ 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.
>
> ##
> # @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
> +#
> +# Since: 2.2
> +##
> +{ 'type': 'BlockdevOptionsNull',
> + 'base': 'BlockdevOptionsFile',
> + 'data': { '*size': 'int' } }
> +
> +##
> # @BlockdevOptionsVVFAT
> #
> # Driver specific block device options for the vvfat protocol.
> @@ -1484,7 +1498,8 @@
> 'vhdx': 'BlockdevOptionsGenericFormat',
> 'vmdk': 'BlockdevOptionsGenericCOWFormat',
> 'vpc': 'BlockdevOptionsGenericFormat',
> - 'quorum': 'BlockdevOptionsQuorum'
> + 'quorum': 'BlockdevOptionsQuorum',
> + 'null': 'BlockdevOptionsNull'
> } }
>
> ##
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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Re: [Qemu-devel] [PATCH v3] block: Introduce "null" driver,
Eric Blake <=