Re: [Qemu-devel] [QEMU][RFC PATCH 4/6] xen-pci: Register PCI in Xen

[Avi Kivity]

On 03/23/2012 01:02 PM, Stefano Stabellini wrote:
> Maybe the best thing to do is to have a set of machine specific options
> to select what devices need to be built in the machine.
> Most devices already can be dynamically selected: NICs, usb, acpi,
> cirrus, etc.
> We already have a Xen machine (xenfv_machine) that uses pc_init1 to
> initialize it.
> We could have a simple bitmask to determine what devices need to be
> enabled, then in pc_init1 we could have something like:
>
> if (devices & VGA_ENABLE) {
>     pc_vga_init();
> }
>
> Given the number of enable variable already present in the code
> (pci_enabled, acpi_enabled, usb_enabled, xen_enabled,
>  cirrus_vga_enabled, ...), it might end up actually making the code more
> readable. The flexibility could end up being useful in the generic case
> as well, for testing if nothing else.
>
> We would still need to call xc_hvm_register_pcidev to register PCI
> devices in Xen, but we wouldn't expect to fail unless there was a
> misconfiguration somewhere. In that case we could just exit.
>
>
>
> Now the problem is: there isn't a simple way to specify the BDF where
> you want to create the device; pci_create_simple takes a devfn but most
> of the higher level functions (pc_vga_init, pci_nic_init_nofail, ...)
> don't export the parameter at the moment.
> We would need to be able to tell pc_vga_init where to create the card,
> so we would have to export the devfn as a parameter.
>

You already have total flexibility with the -device foo parameter.  It
allows you to create any device, anywhere, with whatever configuration
you want.  Use in conjunction with -nodefconfig.

You may want your own host/pci bridge that lacks the device 0
configuration space.

-- 
error compiling committee.c: too many arguments to function