Memtest86+ is an open source stand-alone and self-contained memory tester used to identify bad RAM. To get Memtest86+ working on the Bifferboard we need to make it multiboot compatible since Biffboot is capable of booting multiboot binaries. Attached is both a patch to make Memtest86+ 4.10 multiboot compatible and a compiled binary. The patch is based on the patch for Memtest86+ 4.00 found here with some changes to make it ready for the Bifferboard.
Transferring the Memtest86+ 4.10 binary to the Biffarboard is just like transferring any other kernel using either bb_upload or bb_eth_upload. More information is found on the bootloader page.
Once Memtest86+ 4.10 is transferred enter the Biffboot console and use the "set boottype" command to configure Biffboot to use multiboot. Once that is done Memtest86+ 4.10 should run without any issues except for the Esc button not rebooting the Bifferboard.
Lastly I would like to add that I have attached the Memtest86+ 4.10 source to comply with the GPL and I did try to contact the original patch creator for approval to release my patch before writing this, but since I did not get any reply I decided to go ahead and share it.