Re: MSI-X support on AMD 8132 platforms ?

From: Petr Vandrovec
Date: Tue May 16 2006 - 11:00:34 EST

Andi Kleen wrote:
"Ravinandan Arakali" <ravinandan.arakali@xxxxxxxxxxxx> writes:

I was wondering if anybody has got MSI-X going on AMD 8132 platforms.
Our network card and driver support MSI-X and the combination works
fine on IA64 and xeon platforms. But on the 8132, the MSI-X vectors are
assigned(pci_enable_msix succeeds) but no interrupts get generated.

See erratum #78 in the AMD 8132 Specification update.
It doesn't support the MSI capability and there are no plans to fix that.

AFAIK the only way to get MSI on Opteron is on PCI Express.

I do not think that erratum #78 is related to this - it is related to tunnel itself generating MSI - which is not needed in this case.

Note that with a different OS, MSI-X does work on 8132.

Are you sure?

Can you provide 'lspci -vvvxxx' output from AMD8132 bridge? (esp. bytes 0xF4-0xFF from config space of 1022:7458 devices) By default dword at 0xF4 is 0xA8000008, disabling MSI/MSI-X mapping -> hypertransport interrupts. Changing this to 0xA8010008 should enable this translation (iff qword at 0xF8 is 0x0000FEE00000), allowing MSI to work on respective secondary/subordinate busses. Unfortunately kernel ignores these HT capabilities...

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