Re: [Qemu-devel] [PATCH v2 10/12] block: Allow omitting the file name when using driver-specific options

[Eric Blake <eblake@redhat.com>]

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On 03/20/2013 12:39 PM, Kevin Wolf wrote:
> After this patch, using -drive with an empty file name continues to open
> the file if driver-specific options are used. If no driver-specific
> options are specified, the semantics stay as it was: It defines a drive
> without an inserted medium.
> 
> In order to achieve this, bdrv_open() must be made safe to work with a
> NULL filename parameter. The assumption that is made is that only block
> drivers which implement bdrv_parse_filename() support using driver
> specific options and could therefore work without a filename. These
> drivers must make sure to cope with NULL in their implementation of
> .bdrv_open() (this is only NBD for now). For all other drivers, the
> block layer code will make sure to error out before calling into their
> code - they can't possibly work without a filename.
> 
> Now an NBD connection can be opened like this:
> 
>   qemu-system-x86_64 -drive file.driver=nbd,file.port=1234,file.host=::1
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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