I modded this BIOS according to Fernando’s guide howto-get-full-nvme-support-for-all-systems-with-an-ami-uefi-bios
I wanted to 1) post the details in hopes it helps someone, and 2) Thank the people who put down the knowledge in this forum.
Details:
I used MMTool 4.50.0.23, the latest BIOS on MSI’s support site (E7751IMS.AB0) and inserted NvmExpressDxe_5.ffs. I used the normal BIOS update utility to flash the BIOS. This worked.
What did not work:
I tried Samsung_M2_DXE first and that did not provide boot support. The module showed up in the EFI shell, but wouldn’t boot to the NVMe.
Thanks to Fernando and all the others who have contributed here.