Re: [Qemu-block] [PATCH 18/24] block: Initial implementation of -blockdev

[Eric Blake]

On 02/27/2017 05:20 AM, Markus Armbruster wrote:
> The new command line option -blockdev works like QMP command
> blockdev-add.
> 
> The option argument may be given in JSON syntax, exactly as in QMP.
> Example usage:
> 
>     -blockdev '{"node-name": "foo", "driver": "raw", "file": {"driver": 
> "file", "filename": "foo.img"} }'
> 
> The JSON argument doesn't exactly blend into the existing option
> syntax, so the traditional KEY=VALUE,... syntax is also supported,
> using dotted keys to do the nesting:
> 
>     -blockdev node-name=foo,driver=raw,file.driver=file,file.filename=foo.img
> 
> This does not yet support lists or downstream extensions, i.e. keys
> with __RFQDN_ prefix, but the next few patches will take care of that.
> 
> Note that calling qmp_blockdev_add() (say via qmp_marshal_block_add())
> right away would crash.  We need to stash the configuration for later
> instead.  This is crudely done, and bypasses QemuOpts, even though
> storing configuration is what QemuOpts is for.  Need to revamp option
> infrastructure to support QAPI types like BlockdevOptions.
> 
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
>  qemu-options.hx |  7 +++++++
>  vl.c            | 39 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/qemu-options.hx b/qemu-options.hx
> index bf458f8..8f02264 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -532,6 +532,13 @@ Use @var{file} as CD-ROM image (you cannot use 
> @option{-hdc} and
>  using @file{/dev/cdrom} as filename (@pxref{host_drives}).
>  ETEXI
>  
> +DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
> +    "-blockdev driver[,node-name=N][,discard=ignore|unmap]\n"

Maybe "-blockdev [driver=]DRIVER[,node-name".....

to call out that you use driver as an implied key? But I'm also fine
with what you wrote (it's sufficient enough for a human reading it, and
the help output is not scraped by libvirt).

> +    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
> +    "          [,read-only=on|off][,detect-zeroes=on|off|unmap]\n"
> +    "          [,driver specific parameters...]\n"
> +    "                configure a block backend\n", QEMU_ARCH_ALL)
> +
>  DEF("drive", HAS_ARG, QEMU_OPTION_drive,
>      "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
>      "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"

Reviewed-by: Eric Blake <address@hidden>

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

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