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Re: [Xen-devel] [RFC PATCH 07/12] hvmloader: allocate MMCONFIG area in the MMIO hole + minor code refactoring

On Wed, 30 May 2018 02:13:30 -0600
"Jan Beulich" <JBeulich@xxxxxxxx> wrote:

>>>> On 30.05.18 at 06:32, <x1917x@xxxxxxxxx> wrote:  
>>> On Wed, 30 May 2018 03:56:07 +1000
>>>Alexey G <x1917x@xxxxxxxxx> wrote:
>>>>On Tue, 29 May 2018 08:23:51 -0600
>>>>"Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>>>>>>>> On 12.03.18 at 19:33, <x1917x@xxxxxxxxx> wrote:        
>>>>>> --- a/tools/firmware/hvmloader/config.h
>>>>>> +++ b/tools/firmware/hvmloader/config.h
>>>>>> @@ -53,10 +53,14 @@ extern uint8_t ioapic_version;
>>>>>>  #define PCI_ISA_DEVFN       0x08    /* dev 1, fn 0 */
>>>>>>  #define PCI_ISA_IRQ_MASK    0x0c20U /* ISA IRQs 5,10,11 are PCI 
>>>>>> connected */
>>>>>>  #define PCI_ICH9_LPC_DEVFN  0xf8    /* dev 31, fn 0 */
>>>>>> +#define PCI_MCH_DEVFN       0       /* bus 0, dev 0, func 0 */        
>>>>>Just MCH is liable to become ambiguous in the future. Perhaps 
>>>>Agree, PCI_Q35_MCH_DEVFN is more explicit.  
>> On the other thought, we can reuse one MCH BDF #define for multiple
>> emulated chipsets, not just for something completely distinct to Q35
>> but even for those which mostly require merely changing PCI DIDs (like
>> P35 etc.) So in this case producing multiple #defines like
>> PCI_{Q|P|G}35_MCH_DEVFN for the same BDF 0:0.0 might be excessive.
>> PCI_ICH9_LPC_DEVFN can be actually reused too, its BDF location
>> survived many chipset generations so its #define can be shared as well
>> (though renamed to something like PCI_LPC_BRIDGE_DEVFN).  
>PCI_x35_MCH_DEVFN then, with a brief comment explaining the x?

Hmm, I'm afraid there are too many chipsets sharing similarity with Q35,
including x31 and x33 series. Also, it might be confusing due to
existence of X-series chipsets like Intel X38.

I think it's better to rename this #define to PCI_Q35_MCH_DEVFN for now
as you suggested and leave the choice of unified names  for anyone (if
any) who will be actually adding P35/G35/etc emulation on top of Q35's.
So far we're limited to Q35 after all.

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