RE: MSI-X support on AMD 8132 platforms ?

From: Ravinandan Arakali
Date: Tue May 16 2006 - 14:44:27 EST

Hi Petr,
Thanks for the suggestion.
What you pointed out was the source of the problem. After
enabling the MSI-to-HTInterrupts(the value at offset 0xF6),
I now see interrupts and can ping in both MSI and MSI-X modes.


-----Original Message-----
From: Petr Vandrovec [mailto:vandrove@xxxxxxxxxx]
Sent: Tuesday, May 16, 2006 8:01 AM
To: Andi Kleen
Cc: ravinandan.arakali@xxxxxxxxxxxx; Peter. Phan; Leonid Grossman;
Subject: Re: MSI-X support on AMD 8132 platforms ?

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
0xA8000008, disabling MSI/MSI-X mapping -> hypertransport interrupts.
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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