Re: [Xen-devel] nr_irqs_gsi

[Joe Jin <joe.jin@xxxxxxxxxx>]

On 07/23/12 21:42, Jan Beulich wrote:
>>>> On 12.07.12 at 01:56, Joe Jin <joe.jin@xxxxxxxxxx> wrote:
>> On 07/11/12 17:42, Andrew Cooper wrote:
>>>
>>> No.  There are 55 GSIs, indexed 0 thru 54.  You would be introducing an
>>> off-by-one error by changing the condition.
>>
>> Per xen log, I think it should be 0-55? for it start from 0 yet, please 
>> confirm!
> 
> Indeed it should. And I think it's this line
> 
>     nr_irqs_gsi = max(nr_irqs_gsi, highest_gsi());
> 
> in io_apic.c:init_ioapic_mappings(), which fails to add 1 to the
> result of highest_gsi() (regression from c/s 20076:2b8b6ee95c93).
> 
>>>> (XEN) ACPI: IOAPIC (id[0x00] address[0xfec00000] gsi_base[0])
>>>> (XEN) IOAPIC[0]: apic_id 0, version 32, address 0xfec00000, GSI 0-23
>>>> (XEN) ACPI: IOAPIC (id[0x01] address[0xfec80000] gsi_base[32])
>>>> (XEN) IOAPIC[1]: apic_id 1, version 32, address 0xfec80000, GSI 32-55
> 
> Would you retry with the patch below?
> 
> Jan
> 
> --- a/xen/arch/x86/io_apic.c
> +++ b/xen/arch/x86/io_apic.c
> @@ -2531,7 +2531,9 @@ void __init init_ioapic_mappings(void)
>          }
>      }
>  
> -    nr_irqs_gsi = max(nr_irqs_gsi, highest_gsi());
> +    i = highest_gsi();
> +    if ( i >= nr_irqs_gsi )
> +        nr_irqs_gsi = i + 1;
>  
>      if ( max_gsi_irqs == 0 )
>          max_gsi_irqs = nr_irqs ? nr_irqs / 8 : PAGE_SIZE;
> 
> 
> 
> 
> 

Hi Jan,

I created similar patch for my customer, now waiting their response.

Thanks,
Joe

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