Re: FreeBSD image hangs during boot

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

Aurelien Jarno wrote:
> On Fri, Oct 05, 2007 at 03:25:05PM +0200, Laurent Vivier wrote:
>   
>> Digging in the FreeBSD sources I found the origin of the problem:
>>
>> I added some ACPI traces:
>>
>>    rsirq-0234 [13] RsIrqResource         : Invalid interrupt polarity/trigger in
>>  resource list, 10
>>
>> Which is in /sys/contrib/dev/acpica/rsirq.c :
>>
>>
>>        /*
>>          * Check for HE, LL interrupts
>>          */
>>         switch (Temp8 & 0x09)
>>         {
>>         case 0x01: /* HE */
>>             OutputStruct->Data.Irq.EdgeLevel = ACPI_EDGE_SENSITIVE;
>>             OutputStruct->Data.Irq.ActiveHighLow = ACPI_ACTIVE_HIGH;
>>             break;
>>
>>         case 0x08: /* LL */
>>             OutputStruct->Data.Irq.EdgeLevel = ACPI_LEVEL_SENSITIVE;
>>             OutputStruct->Data.Irq.ActiveHighLow = ACPI_ACTIVE_LOW;
>>             break;
>>
>>         default:
>>             /*
>>              * Only _LL and _HE polarity/trigger interrupts
>>              * are allowed (ACPI spec, section "IRQ Format")
>>              * so 0x00 and 0x09 are illegal.
>>              */
>>             ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
>>                 "Invalid interrupt polarity/trigger in resource list, %X\n", Tem
>> p8));
>>             return_ACPI_STATUS (AE_BAD_DATA);
>>         }
>>
>>     
>
> Good catch!
>
>   
>> Conclusion, in kvm-userspace/bios/acpi-dsdt.dsl, if you have "ActiveHigh", you
>> must have "Edge" instead of "Level":
>>
>> -                    IRQ (Level, ActiveHigh, Shared)
>> +                    IRQ (Edge, ActiveHigh, Shared)
>>
>> But I found nothing in ACPI specification explaining the freeBSD behavior.
>>
>>     
>
>
> It's actually described page 200 of the specifications (page 216 in 
> ACPIspec30.pdf):
>
>   Note: This descriptor is meant for describing interrupts that are connected to PIC-compatible
>   interrupt controllers, which can only be programmed for Active-High-Edge-Triggered or Active-
>   Low-Level-Triggered interrupts. Any other combination is illegal. The Extended Interrupt
>   Descriptor can be used to describe other combinations.
>
>
>   
>> Avi, if you think this anlysis is correct I can provide the patch changing
>> "Level" to "Edge"...
>>
>>     
>
> It looks like the solution is either to describe the IRQ with an 
> "Extended Interrupt Descriptor" or to change this value to one of the 
> two allowed values. In the later case we have to make sure it is
> consistent with the way the PIC works.
>
>   

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.


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


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