Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging

[Anthony Liguori]

On 08/24/2010 08:44 AM, Daniel P. Berrange wrote:
> > > Actually this SCSI example I give above is appending a drive to an existing
> > > bus (scsi0), in slot 1 (scsi-id=1).  To best of my knowledge there is no
> > > remaining use case that requires use of IF_SCSI, IF_IDE, etc. The IF_NONE
> > > approach can cope with all, modulo bugs that appear periodically with code
> > > that mistakenly checks for a particular IF_XXX constant.
> > >
> > > If you wanted to also create a new SCSI bus, before creating the drive on
> > > it, you'd need to run three commands in total:
> > >
> > >    device_add lsi,id=scsi0,bus=pci.0,addr=0x7
> > >    drive_add dummy 
> > > file=/var/lib/libvirt/images/data.img,if=none,id=drive-scsi0-0-1,format=raw
> > >    device_add scsi-disk,bus=scsi0.0,scsi-id=1,drive=drive-scsi0-0-1,id=scsi0-0-1
> > >
> > >        
> > Nice - so we can just deprecate if=!none?
> >      
> In theory yes, but its not nice to tell users to switch everything over to
> use if=none, if we're going to deprecate that too in the next release when
> blockdev appears. Might as well just deprecate entire of drive_add/-drive
> at once.
>    

I think what Alex is really asking is can we have 'blockdev_add 
var0=val0,var1=val1[,...]' implemented as 'drive_add dummy 
if=none,var0=val0,var1=val1[,...]'.  I don't know the answer to why that 
isn't possible or desirable.

Regards,

Anthony Liguori

> Regards,
> Daniel
>