RE: [PATCH 5/7] I/OAT: Add support for MSI and MSI-X

From: Waskiewicz Jr, Peter P
Date: Fri Jul 20 2007 - 14:09:22 EST


> -----Original Message-----
> From: Roland Dreier [mailto:rdreier@xxxxxxxxx]
> Sent: Friday, July 20, 2007 10:43 AM
> To: Nelson, Shannon
> Cc: akpm@xxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> davem@xxxxxxxxxxxxx; jeff@xxxxxxxxxx; Williams, Dan J; Leech,
> Christopher; Waskiewicz Jr, Peter P
> Subject: Re: [PATCH 5/7] I/OAT: Add support for MSI and MSI-X
>
> are there any devices that support MSI but not MSI-X? If
> not, is there any point in having code to support both?
>
> - R.
>

Both igb (recently posted) and ixgbe (also recently posted) support both
MSI and MSI-X. Right now when we try to request MSI-X vectors, if we
fail to acquire what we've asked for, we fall back to MSI support. If
MSI fails to initialize, we fall back to legacy interrupts. So it needs
to be there in case MSI-X allocation fails for the NIC driver.

Thanks,
-PJ Waskiewicz
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