Rafael J. Wysocki wrote:
On Saturday 10 January 2009, Jesse Barnes wrote:
On Thursday, January 8, 2009 12:45 pm Rafael J. Wysocki wrote:
On Thursday 08 January 2009, Rafael J. Wysocki wrote:
On Thursday 08 January 2009, Kenji Kaneshige wrote:
Rafael J. Wysocki wrote:
On Thursday 08 January 2009, Kenji Kaneshige wrote:
Rafael J. Wysocki wrote:
From: Rafael J. Wysocki <rjw@xxxxxxx>
If MSI-X interrupt mode is used by the PCI Express port driver, too
many vectors are allocated and it is not ensured that the right
vectors will be used for various services. Namely, the PCI Express
specification states that both PCI Express native PME and PCI
Express hotplug will always use the same MSI or MSI-X message for
signalling interrupts, which implies that the same vector will be
used by both of them. Also, the VC service does not use interrupts
at all. Moreover, is not clear which of the vectors allocated by
pci_enable_msix() will be used for PME and hotplug and which of
them will be used for AER if all of these services are configured.
For these reasons, rework the allocation of interrupts for PCI
Express ports so that at most two vectors are allocated and ensure
that the right vector will be used for the right purpose.
Appended is a cleaned-up version of the patch that also contains comments
with references to the appropriate sections of the PCI Express spec.
We'll need testing here in any case; I'll have to re-read the specs carefully
to see if we can really rely on the vector numbers you have here (at first
glance Kenji-san's approach seems more robust).
It has a catch too. Namely, is there any warranty that we'll get the same
vectors when the second pci_enable_msix() is called and that they will be in
the same order?
In my understanding, the following description of Interrupt Message
Number in the PCI Express spec explains this.
"[...] For a given MSI-X implementation, the entry must remain constant. [...]"
Thanks,
Kenji Kaneshige
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