Re: PCI Express

Colin Ngam
2005-03-09T18:12:37Z

Nguyen, Tom L wrote:

>On Tue, Mar 08, 2005 at 05:29:13PM -0800, Jesse Barnes wrote:
>...
>
>
>>An MSI should behave like a processor sending an IPI to itself since
>>
>>
>its
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>>address can be targeted at the processor's interrupt block and set to
>>generate a local interrupt. Is that right, Tom & Grant?
>>
>>
>
>MSI address is programmed at 0xfeex_xxxx (based on PCI Specs) to
>
Hi Tom,

The MSI address portion allows 64bits for the address. It should be an
address whereby a specific Platform has configured with sufficient
information to generate an Interrupt to the targeted "cpu" with the
payload - IRQ.

I am very much interested in your assertion that the MSI address is
defined by PCI Spec to be 0xfeex_xxxx. Can you kindly point me to the
relevent section? Perhaps if you have an online copy, can you cut and
paste the relevent section?

Thanks.

colin

>generate a memory write to FSB. This address can be configured to target
>a platform interrupt controller (like IOAPIC for example), which in turn
>generates a memory write to a FSB, or be configured to send a memory
>write directly to FSB. Existing MSI support implements a direct
>memory-write mechanism (generic solution without platform dependency and
>limitation to MSI-X support as an example). With existing direct
>memory-write mechanism, a device's MSI address is configured with
>current running CPU as a target. MSI support also implements MSI SMP
>affinity, which supports IRQ rebalance and allows user to select which
>CPU target through /proc/irq/...
>
>I hope it helps.
>
>Thanks,
>Long
>
>