Re: FreeBSD image hangs during boot

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Laurent Vivier wrote:
>>
>> Edge-triggered means we can't share interrupt lines.  Since we have only 
>> two or three that limits the number of devices we can have.
>>
>> So I'd like to try moving to active low pci interrupts, and implementing 
>> polarity in the qemu ioapic.  It's probably closer to real hardware anyway.
>>
>>     
>
> Avi,
>
> I've two questions:
>
> - why, when you implemented the ioapic polarity bit in kvm (commit 
> 0203e2d5d0d0cea6eed6e437d9456aad71135913, kvm_ioapic_set_irq()), you 
> didn't implement it in qemu (in qemu/hw/apic.c ioapic_set_irq()) ?
>   

Laziness

> - why implementing polarity changes active level in ACPI ?
>   

Qemu has two bugs:

- ACPI (and MP-BIOS) advertises the PCI interrupts as active low
- IOAPIC polarity is not implemented

The bugs cancel each other out.  I fixed one by implementing polarity, 
now we have to fix the other.

-- 
Any sufficiently difficult bug is indistinguishable from a feature.


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