Re: [Qemu-devel] PCI: how handle multifunction / compound devices best?

[Anthony Liguori]

On 07/01/2011 06:27 AM, Gerd Hoffmann wrote:
>    Hi folks,
>
> I'm still looking for a sane way to handle multifunction pci devices,
> specifically a EHCI USB controller with UHCI companion controllers.
>
> Here comes a small (incomplete[1]) two patch series to make the issue
> more clear.  The first patch adds a function which creates all devices
> with the properties set as needed.  The second patch adds a '-usb2'
> switch to windup this in a user-friendly way.
>
> Adding a -usb2 switch sucks though.  I'd prefer to have some way to
> create such devices via -device, but without asking the user to create
> all functions individually on the command line, i.e. have something
> along the lines of ...
>
>   qemu -device ich9-usb,slot=08

This is the place where are current infrastructure pretty much stinks.

The first problem is that the device factory interface should be 
involved with device addressing.  We really should have:

qemu -device ich9-usb,id=uhci0 -set i440fx.slot[8]=uhci0

The device doesn't care what it's PCI slot address is.

ich9-usb should be able to create its functions too as part of its 
initialization.  I don't see an easy answer here unless we do away with 
the current bus model.  There's no way we can do composition given the 
bus model we have.

Best we could do is syntactic sugar for what you have below.

Regards,

Anthony Liguori

> ... instead of ...
>
>   qemu \
>    -device ich9-usb-ehci1,addr=08.7,multifunction=on,id=ehci \
>    -device 
> ich9-usb-uhci1,addr=08.0,multifunction=on,masterbus=ehci.0,firstport=0 \
>    -device 
> ich9-usb-uhci2,addr=08.1,multifunction=on,masterbus=ehci.0,firstport=2 \
>    -device 
> ich9-usb-uhci3,addr=08.2,multifunction=on,masterbus=ehci.0,firstport=4
>
> Suggestions?
>
> cheers,
>    Gerd
>
> [1] full series @ http://www.kraxel.org/cgit/qemu/log/?h=usb.18
>
> Gerd Hoffmann (2):
>    usb: add ich9_ehci_with_companion_init()
>    usb: windup ich9_ehci_with_companion_init via -usb2 switch.
>
>   hw/pc_piix.c    |   14 ++++++++++----
>   hw/usb-ehci.c   |   49 +++++++++++++++++++++++++++++++++++++++++++++++++
>   hw/usb.h        |    3 +++
>   qemu-options.hx |   13 +++++++++++--
>   vl.c            |    3 +++
>   5 files changed, 76 insertions(+), 6 deletions(-)