Re: [Qemu-devel] [PATCH] pci: add standard bridge device

[Wen Congyang]

At 09/08/2011 06:42 PM, Michael S. Tsirkin Write:
> On Thu, Sep 08, 2011 at 05:58:12PM +0800, Wen Congyang wrote:
>> At 09/08/2011 05:43 PM, Gerd Hoffmann Write:
>>>   Hi,
>>>
>>>> I modify the code like this, and the PCI_INTERRUPT_LINE register is
>>>> set, and I can bind
>>>> it to uio_pci_generic:
>>>
>>>> --- a/src/pciinit.c
>>>> +++ b/src/pciinit.c
>>>> @@ -575,6 +575,8 @@ static int pci_bios_init_root_regions(u32 start,
>>>> u32 end)
>>>
>>>>       pci_bios_init_bus_bases(&busses[0]);
>>>> -    pci_bios_map_device_in_bus(0 /* host bus */);
>>>> +    for (bus = 0; bus<= MaxPCIBus; bus++) {
>>>> +        pci_bios_map_device_in_bus(bus /* host bus */);
>>>
>>> No.  pci_bios_map_device_in_bus goes down recursively when it finds a
>>> bridge, so it should cover all devices already.
>>
>> Yes, pci_bios_map_device() goes down recursively.
> 
> The value seems to be wrong though, I think.
> It seems to simply use the interrupt pin as array index.
> Instead, each bridge should interrupts as follows:
> 
> /* Mapping mandated by PCI-to-PCI Bridge architecture specification,
>  * revision 1.2 */
> /* Table 9-1: Interrupt Binding for Devices Behind a Bridge */
> static int pci_bridge_dev_map_irq_fn(PCIDevice *dev, int irq_num)
> {
>     return (irq_num + PCI_SLOT(dev->devfn)) % PCI_NUM_PINS;
> }
> 
> until we get to the host bridge.

I use gdb to debug, and find that this function is never called.

Thanks
Wen Congyang

> 
> 
>>>
>>>> -    pci_bios_init_device_in_bus(0 /* host bus */);
>>>> +        pci_bios_init_device_in_bus(bus /* host bus */);
>>>> +    }
>>>
>>> That is correct.  Can be done easier though by just not limiting device
>>> initialization to a specific bus like in the attached patch.  Does that
>>> one work for you?
>>
>> I test it, and it works for me.
>>
>> Thanks
>> Wen Congyang
>>
>>>
>>> cheers,
>>>   Gerd
>