Hi John,
John Keller wrote:
Hi,
This is FYI.
If VECTOR_DOMAIN_PERCPU is NOT enabled:
The "irq == vector" is always true in the following cases:
- reserve_irq_vector(), which is used only by SN
- create_irq() used on the system that has NO I/O SAPIC
Could you say a bit more about this case. I see create_irq()
calling find_unassigned_vector() and find_unassigned_irq().
How is "irq == vector" guaranteed to be always true in this case?
It's guaranteed as follows:
- When find_unassigned_vector()/find_unassigned_irq() search
available vector and irq, it always start to search from
IA64_FIRST_DEVICE_VECTOR.
- clear_irq_vector() releases both vector and irq.
Thanks,
Yasuaki
John
- assign_irq_vector() with AUTO_ASSIGN specified
- Vectors outside FIRST_DEVICE_VECTOR to LAST_DEVICE_VECTOR
The "irq == vector" is not always true in the folliwng cases:
- create_irq() used on the system that has I/O SAPICs.
- assign_irq_vector() with the value other than AUTO_ASSIGN
specified on the system has I/O SAPICs.
And it is not ensured that those are true even in the future.
Yasuaki, could you check if it is correct?
Thanks,
Kenji Kaneshige
2007-08-02 (木) の 08:26 -0500 に John Keller
さんは書きました:
Yes, we'll take a look at it.
John
Hi Kenji-san
I believe we need this property, but I am not 100% sure, so I am
going to forward your patch to our team who maintain the IRQ code
for Altix.
Mike, Aaron or John, would one of you have time to take a look at
this?
Thanks,
Jes
Kenji Kaneshige wrote:
Hi Jes-san, Russ-san, Christoph-san and SN platform developers,
I glanced over the SN code, and I found SN platform doesn't have SN
specific irq_to_vector() function, though it has SN specific
local_vector_to_irq() function. I guess it was OK because maybe SN
platform depends on irq == vector and old generic irq_to_vector() was
just returning the same value as irq.
The irq_to_vector() function, however, has been changed by vector
domain support, and currently it can return the different value from
irq, even when VECTOR_DOMAIN_PERCPU is not enabled. This can happen
when an interrupt thorough I/O SAPIC is unregistered and another
interupt is registered. So if my guess (SN platform depends on irq ==
vector) is true, something problem might happen on SN platform when
PCI hotplugging or driver reloading.
If it is true that SN platform depends on irq == vector, we need to
implement SN specific irq_to_vector() that returns the same value as
irq, I think. I made sample patches to implement platform specific
irq_to_vector() as follows. Note that [PATCH 2/2] is not tested yet
because I don't have any SN platform unfortunately.
[PATCH 1/2] Add base support for platform_irq_to_vector()
[PATCH 2/2] Implement platform_irq_to_vector() for SN
Could you give me comments?
Thanks,
Kenji Kaneshige
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