I thought some of you would be interested in this issue.
I was missing the memtest86+ that used to be accessible from the grub
menu. I see it is installed...
$ apt-cache policy memtest86+
memtest86+:
Installed: 5.01-3ubuntu2
Candidate: 5.01-3ubuntu2
Version table:
*** 5.01-3ubuntu2 500
500 http://us.archive.ubuntu.com/ubuntu artful/main amd64 Packages
100 /var/lib/dpkg/status
...but it turns out that the problem is that with UEFI we can't run it, so
it isn't in the boot menu anymore with UEFI systems. But with UEFI we can
use this free (gratis) solution which I think is not free (libre)
software:
https://www.memtest86.com/download.htm
I decided to use it anyway. I downloaded the Linux/Mac "Image for
creating bootable USB Drive" and followed the README instructions. It was
pretty straightforward. I made one mistake: I saw that the USB was
mounted as /dev/sdg1, so I used that for "<dev>" in the dd command, but
that didn't work. The right answer was to use /dev/sdg instead.
Booting from the USB then ran the test.
Best,
Mike