Cisco 12G SAS RAID support (FreeBSD 12.1-RELEASE) ?

[Chris Ross]

Hello.  I have a Cisco UCS C220-M5 with a RAID controller.  It calls itself
"Cisco 12G Modular Raid Controller with 2GB cache", PPID UCSC-RAID-M5.
Looking at the CIMC, it shows the PCI vendor/device ids 1000:0014, which
looks to be an LSI MegaRAID Tri-Mode SAS3516.  It looks like this should
be supported by the mpr(4) driver, but it doesn't seem to recognize it
at boot time.  Is there some magic I need to perform for the 12.1-RELEASE
image ISO boot to get this driver loaded, or will some internal changes
be needed to support this particular part due to quirks?

Let me know any information I can provide that will help diagnose.  Thank
you.

              - Chris