[Qemu-devel] Re: [PATCH v3 08/13] pcie root port: implement pcie root port.

[Michael S. Tsirkin]

On Mon, Sep 27, 2010 at 03:22:43PM +0900, Isaku Yamahata wrote:
> On Sun, Sep 26, 2010 at 02:50:42PM +0200, Michael S. Tsirkin wrote:
> > On Fri, Sep 24, 2010 at 02:38:09PM +0900, Isaku Yamahata wrote:
> > > On Wed, Sep 22, 2010 at 01:25:59PM +0200, Michael S. Tsirkin wrote:
> > > 
> > > > > +PCIESlot *pcie_root_init(PCIBus *bus, int devfn, bool multifunction,
> > > > > +                         const char *bus_name, pci_map_irq_fn 
> > > > > map_irq,
> > > > > +                         uint8_t port, uint8_t chassis, uint16_t 
> > > > > slot);
> > > > > +
> > > > 
> > > > I am a bit unhappy about all these _init functions.
> > > > Can devices be created with qdev? If they were
> > > > it would be possible to configure the system completely
> > > > from qemu command line.
> > > 
> > > That's very reasonable question.
> > > Once machine configuration file is supported, those initialization
> > > functions will go away.
> > > I.e. when the initialization code like pc_init1() in pc_piix.c disappears,
> > > those functions will also go away.
> > > 
> > > Until that, those initialization glues will stay like pci_create family
> > > or other many initialization glues unfortunately.
> > > This is the result of qdev missing a feature, not the cause.
> > > It would be a long-term issue to add machine configuration file support.
> > 
> > Just to clarify, if I wanted to have a flag to make virtio-net
> > a pci express device, how would I do this?
> 
> the following preparation is needed.
> - register PCIDeviceInfo with name like "virtio-net-pci-xen"
>   with PCIDeviceInfo::is_express = true.
> - in initialization function, initialize express capability.
> - in write config function, call related function.
> 
> And then,
> if (express)
>    create "virtio-net-pci-xen"
> else
>    create "virtio-net-pci"

Sounds pretty bad: we can't double the number of devices
with each capability we add.
Can we make it so setting is_express on command line
will convert the device to PCI express?


> -- 
> yamahata