Xen devel - Nov 2006 - RE: [PATCH] Change spec of callback IRQ for PV-on-HVM onIA64

>From: DOI Tsunehisa
>Sent: 2006年11月21日 12:46
>
>  * pvdrv.patch2
>    - Modify to change the spec of callback IRQ in PV-driver side.
>    - This patch brakes compatibility with previous version on IA64.
>
>  I tested with our simple test of PV-on-HVM on RHEL4 U2 for IA64
>with hypervisor side modification.
>
>Thanks,
>- Tsunehisa Doi
Maybe I''m missing something and you can help me understand. :-) 
Whatever the value is mangled in pdev->irq, you should always 
keep following two instances same:
	if ((ret = request_irq(pdev->irq, evtchn_interrupt, SA_SHIRQ,...
and
	if ((ret = set_callback_irq(pdev->irq)))

Before your patch, say pdev->irq is 0x27 (ISA irq 9), platform-pci 
driver binds handler to 0x27 and xen will inject by callback_irq 0x27. 
However in your patch, request_irq is still using pdev->irq (0x27) 
while set_callback_irq instead wants (0x9). In this case, how can you 
still make things working when two sides don''t match...

Thanks,
Kevin

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Hi Kevin,

You (kevin.tian) said:
>>  * pvdrv.patch2
>>    - Modify to change the spec of callback IRQ in PV-driver side.
>>    - This patch brakes compatibility with previous version on IA64.
>>
>>  I tested with our simple test of PV-on-HVM on RHEL4 U2 for IA64
>>with hypervisor side modification.
>>
>>Thanks,
>>- Tsunehisa Doi
> 
> Maybe I''m missing something and you can help me understand. :-) 
> Whatever the value is mangled in pdev->irq, you should always 
> keep following two instances same:
> 	if ((ret = request_irq(pdev->irq, evtchn_interrupt, SA_SHIRQ,...
> and
> 	if ((ret = set_callback_irq(pdev->irq)))
  In x86-linux, two instances are same. But in IA64-linux, previous one
is a external interrupt vector for xen-platform interruption. Although
latter one is a hardware IRQ id. Both values are not same in IA64-linux.
> Before your patch, say pdev->irq is 0x27 (ISA irq 9), platform-pci 
> driver binds handler to 0x27 and xen will inject by callback_irq 0x27. 
> However in your patch, request_irq is still using pdev->irq (0x27) 
> while set_callback_irq instead wants (0x9). In this case, how can you 
> still make things working when two sides don''t match...
  With the modification of hypervisor side, the callback_irq(it''s
hardware
IRQ) becomes to be converted to external interrupt vector with a emulator
of IOSAPIC.

Thanks,
- Tsunehisa Doi

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You (Doi.Tsunehisa) said:
>> Maybe I''m missing something and you can help me understand.
:-)
>> Whatever the value is mangled in pdev->irq, you should always 
>> keep following two instances same:
>> 	if ((ret = request_irq(pdev->irq, evtchn_interrupt, SA_SHIRQ,...
>> and
>> 	if ((ret = set_callback_irq(pdev->irq)))
> 
>   In x86-linux, two instances are same. But in IA64-linux, previous one
> is a external interrupt vector for xen-platform interruption. Although
> latter one is a hardware IRQ id. Both values are not same in IA64-linux.
  Sorry.. This description is situation with my patch.
--
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