Re: [PATCH v2] hw/sparc64/sun4u: Mark unusable PCI busses as full to ease device plugging

On 07/07/2026 09:42, Philippe Mathieu-Daudé wrote:

> On 6/7/26 23:19, Philippe Mathieu-Daudé wrote:
>> On 6/7/26 23:16, Mark Cave-Ayland wrote:
>>> On 06/07/2026 21:29, Philippe Mathieu-Daudé wrote:
>>>
> 
>>>>> -    pci_bus = PCI_HOST_BRIDGE(sabre)->bus;
>>>>>       pci_busA = pci_bridge_get_sec_bus(sabre->bridgeA);
>>>>>       pci_busB = pci_bridge_get_sec_bus(sabre->bridgeB);
>>>>>
>>>>> -    /* Only in-built Simba APBs can exist on the root bus, slot 0 on busA is
>>>>> -       reserved (leaving no slots free after on-board devices) however slots
>>>>> -       0-3 are free on busB */
>>>>> -    pci_bus_set_slot_reserved_mask(pci_bus, 0xfffffffc);
>>>>> +    /*
>>>>> +     * Slot 0 on busA is reserved (leaving no slots free after on- board
>>>>> +     * devices) however slots 0-3 are free on busB
>>>>> +     */
>>>>>       pci_bus_set_slot_reserved_mask(pci_busA, 0xfffffff1);
>>>>>       pci_bus_set_slot_reserved_mask(pci_busB, 0xfffffff0);
>>>>>
>>>>> ---
>>>>>
>>>>> I'm still looking at the 2nd part, the reserved slots.
>>>>
>>>> (Because with this patch, the test passes as we can plug devices from
>>>> the command line, but they end plugged on pciA instead of pciB -- thus
>>>> the 2nd part missing).
>>>
>>> Thanks for taking a look, Phil. IIRC the reason I added slot_reserved_mask was so 
>>> that it was possible to populate pciA programatically in sun4uv_init(), and then 
>>> enable the mask so that specifying an additional PCI device using -device on the 
>>> command line without an explict PCI bus would cause the automatic allocation to 
>>> place the device on pciB.
>>
>> The slot_reserved_mask calls make sense, but AFAICT they don't work as
>> expected, since CLI devices are added on pciA. If you want to have a
>> look on top of this snippet, be my guest! Otherwise I'll continue
>> debugging that tomorrow, long day and late here :\
> 
> Generic PCI fix posted here:
> https://lore.kernel.org/qemu-devel/[email protected]/

Thanks Phil! I can confirm that this solves the issue for me.


ATB,

Mark.