Re: [Qemu-ppc] [PATCH 3/4] spapr: Code more defensively against lack of primary PCI bus

[Alexander Graf]

Am 30.04.2013 um 13:15 schrieb Alexey Kardashevskiy <address@hidden>:

> On 04/30/2013 07:45 PM, Alexander Graf wrote:
>> 
>> On 30.04.2013, at 06:33, Alexey Kardashevskiy wrote:
>> 
>>> Currently sPAPR always creates a primary PCI host bridge for emulated PCI
>>> devices.  However, because the platform supports native virtual IO, and
>>> can also support multiple independent PCI host bridges, it's quite often
>>> useful to disable the primary bridge for debugging purposes.
>>> 
>>> This patch, therefore, makes the code cope more gracefully with a missing
>>> primary host bridge.
>> 
>> Does this handle the -net case too? What about disks?
>> 
>> If those use a different mechanism to find their bus, maybe it'd be better 
>> to instead do
>> 
>> if (phb) {
>>    pcibus = phb->bus;
>> } else {
>>    pcibus = find_pci_bus();
>> }
>> 
>> In fact, maybe the code already deals with bus==NULL?
> 
> 
> I needed it to deal with phb==NULL.
> 
> The story behind this patch is that while doing VFIO stuff, I have to deal
> with multiple PHBs. And sometime I want to be 100% sure that it is just
> VFIO PHB and no emulated PCI stuff (especially when I debug USB PCI card in
> VFIO) so I simply commented out the call which creates default emulated PHB
> and that would be it if the existing code did not try to use phb->bus.

Then this code does nor belong in upstream. If you want to have full control 
over instantiated devices, implement -nodefaults.


Alex

> 
> 
> 
> 
>> 
>> 
>> Alex
>> 
>>> 
>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>>> Signed-off-by: David Gibson <address@hidden>
>>> ---
>>> hw/ppc/spapr.c |    6 +++---
>>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>> 
>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>>> index c96ac81..d07c74a 100644
>>> --- a/hw/ppc/spapr.c
>>> +++ b/hw/ppc/spapr.c
>>> @@ -732,7 +732,7 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
>>>    const char *boot_device = args->boot_device;
>>>    PowerPCCPU *cpu;
>>>    CPUPPCState *env;
>>> -    PCIHostState *phb;
>>> +    PCIHostState *phb = NULL;
>>>    int i;
>>>    MemoryRegion *sysmem = get_system_memory();
>>>    MemoryRegion *ram = g_new(MemoryRegion, 1);
>>> @@ -898,11 +898,11 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
>>>    }
>>> 
>>>    /* Graphics */
>>> -    if (spapr_vga_init(phb->bus)) {
>>> +    if (phb && spapr_vga_init(phb->bus)) {
>>>        spapr->has_graphics = true;
>>>    }
>>> 
>>> -    if (usb_enabled(spapr->has_graphics)) {
>>> +    if (phb && usb_enabled(spapr->has_graphics)) {
>>>        pci_create_simple(phb->bus, -1, "pci-ohci");
>>>        if (spapr->has_graphics) {
>>>            usbdevice_create("keyboard");
>>> -- 
>>> 1.7.10.4
> 
> 
> -- 
> Alexey