Re: [Qemu-devel] unable to use device_add command to hot plug storage volumes to an instance.

[Vinay Venkataraghavan]

Hi all,

I'm still encountering this issue that I've described below. 


I think prior to qemu 0.12 qemu used to support the pci_add pci_addr=auto 
storage file=<filename> interface to hot plug/ hot add storage volumes to a 
running instance. 


However, the pci_add command is not supported in 0.12 at all. When did this 
happen? 


Secondly, now how can I achieve this for qemu 0.12? 


I've tried using the device_add interface and the documentation says that it 
should be very similar to the -device options on the command line when 
launching new instances. However, this just is not the case. I've been trying 
all sorts of experiments to no avail.

I have a few related questions:

1. I connect to my instance using socat on the unix socket/monitor interface. 


    i try passing commands like: (qemu) device_add 
driver=virtio-blk-pci,drive=/root/test_file etc

   and this fails. 


I've tried a number of other options as well and none of them seem to work.

Secondly, do the inputs to device_add need to be in a JSON dictionary format? 


Thirdly, what is the expected input for the drive parameter? There seems to be 
no documentation describing exactly how this needs to be handled at all. Any 
help would be greatly appreciated. 

(qemu) device_add driver=virtio-blk-pci,bus=pci.0,addr=0x6,?
device_add driver=virtio-blk-pci,bus=pci.0,addr=0x6,?
virtio-blk-pci.class=hex32
virtio-blk-pci.drive=drive
virtio-blk-pci.logical_block_size=uint16
virtio-blk-pci.physical_block_size=uint16
virtio-blk-pci.min_io_size=uint16
virtio-blk-pci.opt_io_size=uint32
virtio-blk-pci.vectors=uint32
virtio-blk-pci.indirect_desc=on/off
virtio-blk-pci.scsi=on/off

So it has all these options but what are the valid values for the drive 
parameter?



Thanks,
- Vinay





----- Original Message -----
From: Markus Armbruster <address@hidden>
To: Vinay Venkataraghavan <address@hidden>
Cc: "address@hidden" <address@hidden>
Sent: Monday, July 25, 2011 8:41 AM
Subject: Re: [Qemu-devel] qemu 0.12 monitor command syntax and interface

Vinay Venkataraghavan <address@hidden> writes:

> Hi all,
>
> I am implementing a generic interface that supports qemu versions 0.9 to 
> 0.12. 
>
>
> As a result I have been trying to get the syntax for the monitor commands for 
> various qemu versions. I have scrounged all over but have not been able to 
> find the syntax for the device_add interface which is supported in qemu 0.12.
>
> I would really appreciate it if someone could point me to the syntax for 
> these commands. The help text does not provide sufficient information about 
> the argument list either:
>
> I tried many versions of this command but to no avail:
>
> device_add 
> driver=virtio-blk-pci,bus=pci.0,addr=0x6,drive=/tmp/ec6f5d90-e734-4539-bd05-d7545e0f8323.img
>  

Not what you're asking for, but better than nothing:
docs/qdev-device-use.txt

> Lastly does the device_add commands deprecate the pci_add commands or 
> generically do the device_* commands deprecate the pci_* commands?

In my opinion, yes.