Re: [Qemu-devel] [PATCH v2 5/7] qmp: add set-bootindex command

[Gonglei (Arei)]

Hi,

> >> Subject: Re: [Qemu-devel] [PATCH v2 5/7] qmp: add set-bootindex command
> >>
> >> On Fri, Jul 25, 2014 at 02:52:50PM +0800, address@hidden wrote:
> >> > From: Gonglei <address@hidden>
> >> >
> >> > Adds "set-bootindex id=xx,bootindex=xx,suffix=xx" QMP command.
> >> >
> >> > Example QMP command:
> >> > -> { "execute": "set-bootindex", "arguments": { "id": "ide0-0-1",
> >> > "bootindex":
> >> 1, "suffix": "/address@hidden"}}
> >> > <- { "return": {} }
> >> >
> >> > Signed-off-by: Gonglei <address@hidden>
> >> > Signed-off-by: Chenliang <address@hidden>
> >> > ---
> >> >  qapi-schema.json | 16 ++++++++++++++++
> >> >  qmp-commands.hx  | 24 ++++++++++++++++++++++++
> >> >  qmp.c            | 17 +++++++++++++++++
> >> >  3 files changed, 57 insertions(+)
> >> >
> >> > diff --git a/qapi-schema.json b/qapi-schema.json
> >> > index b11aad2..a9ef0be 100644
> >> > --- a/qapi-schema.json
> >> > +++ b/qapi-schema.json
> >> > @@ -1704,6 +1704,22 @@
> >> >  { 'command': 'device_del', 'data': {'id': 'str'} }
> >> >
> >> >  ##
> >> > +# @set-bootindex:
> >> > +#
> >> > +# set bootindex of a devcie
> >> > +#
> >> > +# @id: the name of the device
> >> > +# @bootindex: the bootindex of the device
> >> > +# @suffix: #optional a suffix of the device
> >> > +#
> >> > +# Returns: Nothing on success
> >> > +#          If @id is not a valid device, DeviceNotFound
> >> > +#
> >> > +# Since: 2.2
> >> > +##
> >> > +{ 'command': 'set-bootindex', 'data': {'id': 'str', 'bootindex':
> >> > int', '*suffix':
> >> 'str'} }
> >> > +
> >> > +##
> >>
> >> I wonder if we could simply use qom-set for that. How many devices
> >> actually support having multiple bootindex entries with different
> >> suffixes?
> >>
> > AFAICT, the floppy device support two bootindex with different suffixes.
> 
> Block device models commonly a single block device.  By convention,
> property "drive" is the backend, and property "bootindex" the bootindex,
> if the device model supports that.
> 
> The device ID suffices to identify a block device for such device
> models.
> 
> The floppy device model is an exception.  It folds multiple real-world
> objects into one: the controller and the actual drives.  Have a look at
> -device isa-fdc,help:
> 
>     isa-fdc.iobase=uint32
>     isa-fdc.irq=uint32
>     isa-fdc.dma=uint32
>     isa-fdc.driveA=drive
>     isa-fdc.driveB=drive
>     isa-fdc.bootindexA=int32
>     isa-fdc.bootindexB=int32
>     isa-fdc.check_media_rate=on/off
> 
> The properties ending with 'A' or 'B' apply to the first and the second
> drive, the others to the controller.
> 
> Unfortunately, this means the device ID by itself doesn't identify the
> floppy device.
> 
Yes.

> Arguably, this is lousy modeling --- we really should model separate
> real-world objects as separate objects.  But making floppies pretty (or
> even sane) isn't anyone's priority nowadays.
> 
Hmm... Agreed.

> Since qom-set works on *properties*, I can't see why it couldn't be used
> for changing bootindexes.  There is no ambiguity even with floppy.

Sorry? 

> You either set bootindexA or bootindexB.  No need to fuzz around with
> suffixes.  Or am I missing something?

Your mean that we just need to think about change one bootindex? Either 
set bootindexA or bootindexB, do not need pass suffix for identifying?

Best regards,
-Gonglei