Avi Kivity wrote:
> Xu, Anthony wrote:
>> Hi all,
>> Thanks for your comments.
>>
>> I made this new patch based on your comments
>>
>> 1. use bimodal _PRT, to take advantage of IOAPIC pin 16~23
>> the mapping is simple, slot -> (slot&7)+16 IOAPIC pin,
>> someone may provide good mapping ?
>>
>
> I think it's fine. If we find a better one later, or if we add another
> ioapic, we can easily change it since the bios and qemu are shipped
> as a unit.
>
>> 2. use ISA-bridge configure space 0x64 byte as a communication
>> mechansim. When guest BIOS invokes _PIC, the value is passed to
qemu
>> through byte 0x64.
>> qemu know whether it is PIC mode and APIC mode by
>> checking byte 0x64.
>> 3. pci_slot_get_pirq and piix3_set_irq adopt different operation
>> based on PIC mode/APIC mode
>>
>
> I'm not sure how real hardware works, but I _think_ that it routes
> irqs unconditionally to both the legacy path and directly to the
> ioapic. So for example if slot 5 asserts an interrupt, we map it
> through the pci link mapping and generate an active high interrupt to
> one of {5, 10, 11} (both pic and ioapic), and simultaneously an
> active low interrupt to ioapic pin 21.
I think what you described is correct.
>
> The _PIC method should disable the link interrupts if ioapic mode is
> disabled.
Typo! If ioapic mode is enabled.
>From x86 BIOS, OS disable link interrupt through link device _DIS
mothod.
>
> This removes the need for communication between the bios and qemu.
Agree
>
>>
>> + /* APIC and PIC flag */
>> + OperationRegion (P40D, PCI_Config, 0x64, 0x01) +
>>
>
> This is actually SERIRQC, serial irq control.
>
>> +
>> +#ifdef KVM_CAP_IRQCHIP
>>
>
> This should be unconditional.
>
>> +static int pci_slot_get_pirq(PCIDevice *pci_dev, int irq_num) +{
>> + int slot_addend;
>> + if( piix3_dev->config[0x64]) // APIC mode
>> + return ((pci_dev->devfn >> 3) & 7)+16;
>> + else { // PIC mode
>> + slot_addend = (pci_dev->devfn >> 3) - 1;
>> + return (irq_num + slot_addend) & 3;
>> + }
>> +}
>>
>
> What I'm suggesting is to "fork" the interrupt into two lines, one
> legacy path and the ioapic path.
I'll try this way.
Anthony
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