Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Sun, 8 Jan 2023 20:10:57 -0800

On 1/5/23 23:15, 문건영(선형가속기팀) via Tech-talk wrote:

I can distinguish the two EVRs after the IOC runs.

Is there any way to know before the IOC is implemented?

In an ideal world, the MTCA slot numbers would be reflected in Linux and be the best way to
know which card is which.  lspci would show this as "Physical Slot" [1].  Unfortunately,
If you don't see this then you are likely out of luck.

An EVR can be distinguished from an EVG by inspecting MRF specific identify registers.
The mrfioc2 driver does this test at startup.  imo. it is simpler to startup an IOC.

I don't know of a good way to distinguish two identical MRF cards in an unknown MTCA crate
without either removing one of them, causing an LED on one to blink, or connecting an
oscilloscope.

That said, I have found that the PCI bus id numbers are deterministic unless the physical
PCIe bus topology changes.  eg. by adding or removing bridge devices.  So with a set of
identical MTCA crate configurations, the PCI id numbers should be predictable.

A caveat to this is that some PCIe bus topology changes may be outside of your control
depending on how MTCA firmwares and Linux combine to handle bus enumeration.

[1] https://github.com/epics-modules/mrfioc2/blob/a8cb48d549b7aae13206cf2d168c6f1cfec2e1c4/documentation/lspci/mtca-evm-300.txt#L3

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System