Re: Can not use hmp block_resize command with -blockdev option

[LKML <xiaojun.zhao141@gmail.com>]

On Thu, 18 Mar 2021 17:17:50 +0100
Kevin Wolf <kwolf@redhat.com> wrote:

> Am 18.03.2021 um 16:15 hat zhao xiaojun geschrieben:
> > Thanks you, that's really good idea. And I also have the following
> > question:
> > 
> > There are some hmp and qmp commands in my scripts, they need the
> > device as an argument. Recently. i used the -blockdev replace the
> > -drive to specify the disk drive, then use  qmp's query_block to
> > query the device, but the device is NULL string. For the hmp's
> > block_resize, I can use qmp's block_resize do. But the other
> > commands(qpm's block-job-cancel etc.), they only support the device
> > argument. So I can only continue to use -drive to specify disk
> > drive.
> > 
> > I was trying to see the source(qemu v5.1.0):
> > qmp_query_device()  
> >   -> bdrv_query_info()  
> >       info->device = g_strdup(blk_name(blk))
> > the device is set to blk_name(blk), and the blk->name is set in
> > the monitor_add_blk()
> > 
> > the -blockdev:
> > qmp_blockdev_add()  
> >    -> bds_tree_init()
> >      -> bdrv_open()  
> >    ...
> > the qmp_blockdev_add() doesn't call the monitor_add_blk().
> > 
> > Questions:
> > Why can not qmp_blockdev_add() call the monitor_add_blk()?
> > Will the hmp and qmp commands that only support device as an
> > argument be compat with the -blockdev option?  
> 
> QMP doesn't have such commands. For commands that operate on the
> frontend (the guest device), they accept the id of the -device. For
> commands that relate to the backend, you can specify node-name.
> 
> It's only HMP that may not support these alternatives in some places.
> We can just extend it.
> 
> Kevin
> 

Ok, thank you very much.

Regards.