Using IOAT PMD

[Bruce Richardson]

On Thu, Dec 16, 2021 at 11:04:54AM -0500, Lance Richardson wrote:
> Hi Bruce,
> 
> I've been looking into using the IOAT PMD, initially with dma_autotest
> and the dpdk-dma example application. These seem to work fine on
> SKX with the current main branch, but when I try the same procedure
> on ICX (binding all 8 devices to vfio-pci in both cases), I get the following
> output for each device when probed. Is something different needed when
> using IOAT on ICX vs. SKX?
> 
> Thanks,
>      Lance
> 
> EAL: Probe PCI driver: dmadev_ioat (8086:b00) device: 0000:80:01.0 (socket 2)
> IOAT: ioat_dmadev_probe(): Init 0000:80:01.0 on NUMA node 2
> IOAT: ioat_dmadev_create(): ioat_dmadev_create: Channel count == 255
> 
> IOAT: ioat_dmadev_create(): ioat_dmadev_create: Channel appears locked
> 
> IOAT: ioat_dmadev_create(): ioat_dmadev_create: cannot reset device.
> CHANCMD=0xff, CHANSTS=0xffffffffffffffff, CHANERR=0xffffffff
> 
> EAL: Releasing PCI mapped resource for 0000:80:01.0
> EAL: Calling pci_unmap_resource for 0000:80:01.0 at 0x4102430000
> EAL: Requested device 0000:80:01.0 cannot be used

That is strange, the same PMD should work ok on both platforms. This is all
on latest branch, right? Let me attempt to reproduce and get back to you.

/Bruce

PS: Is this a 4-socket system you are running on, since I see "socket 2"
being described as the socket number for device 80:01.0?