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wonsikleee
Observer
Observer
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Registered: ‎11-12-2019

How to use multiple xdma core in a board?

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Hi,

I'm using u250 board with ubuntu 18.04 LTS.

If I add multiple xdma core in my design, then how can I detect each core with device driver?

It seems that I can name each core but I don't know how to do it.

Best,

Wonsik

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mcertosi
Xilinx Employee
Xilinx Employee
579 Views
Registered: ‎10-19-2015

Hi @wonsikleee 

The host's abilities should be listed with the host's user guide. 

See this discussion: 

https://serverfault.com/questions/975464/does-dell-poweredge-r720xd-support-pcie-bifurcation 

The server needs to have the hardware capablities listed in the server or motherboard's user guide. Then you'll usually need to enable bifurcation in the bios. 

Keep in mind the Alveo cards are pinned out to support a x16 to x8 bifrication so x4 x4 x4 x4 bifurcation will not work.

-M

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mcertosi
Xilinx Employee
Xilinx Employee
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Registered: ‎10-19-2015

Hi @wonsikleee 

This doesn't sound like a standard approach. I'm wondering why you are interested in two XDMA cores in your design. The DMA cores mate with PCIe and it is very likely you only have one PCIe connection. 

Could you give me more details on what you are looking to do so I could try to look into this further? 

Regards,

M

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wonsikleee
Observer
Observer
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Registered: ‎11-12-2019

 

Hi, mcertosi

I'm wondering if I set the number of PCIe lane lower than the physical lane(e.g., x4) when I set the core setting, then can I separately communicate with the host with two xdma cores.

For example, if I have two xdma cores and they are using x4 or x8 PCIe lane bandwidth, then can I use communicate with the host using those cores separately?

Thanks,

Wonsik

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bethe
Xilinx Employee
Xilinx Employee
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Registered: ‎12-10-2013

Hi @wonsikleee 

The Alveo cards are pinned out to support a x16 to x8 bifrication.  This means that you can connect 2 DMA/Bridge cores to the physical lanes and *if the host is capable* communicate in a dual x8.   This would need to be done in the Custom Flow (Vivado), as we have no Shells to date that do this.  You would also need to use the XDMA general host drivers (found on the Github) rather than the Vitis / XRT Acceleration drivers.

The XDC published with the cards should allow you to determine which PCIe cores and quads will need to be used, as well as the second MGT clock.   Each clock will need to be driven from the slot.

As far as the driver is concerned, the driver should create an instance for each core and attach. 

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wonsikleee
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Registered: ‎11-12-2019

 

Thanks for your quick reply, @bethe 

Would you provide more details for "If the host is capable communicate in a dual x8"?

Is this related only to the driver? or anything else?

Thanks,

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mcertosi
Xilinx Employee
Xilinx Employee
580 Views
Registered: ‎10-19-2015

Hi @wonsikleee 

The host's abilities should be listed with the host's user guide. 

See this discussion: 

https://serverfault.com/questions/975464/does-dell-poweredge-r720xd-support-pcie-bifurcation 

The server needs to have the hardware capablities listed in the server or motherboard's user guide. Then you'll usually need to enable bifurcation in the bios. 

Keep in mind the Alveo cards are pinned out to support a x16 to x8 bifrication so x4 x4 x4 x4 bifurcation will not work.

-M

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