memtest86+ is memory test software based on the (commercially available) memtest86 program.
Memtest86+ does not support UEFI. You can switch to Memtest86 V5 or newer for UEFI supported memtesting.
Be sure /boot (where the GRUB files are typically installed) is available before installing memtest86+! If /boot is on a separate partition (which it WILL BE if the partitioning scheme in the Gentoo handbook was used for this Gentoo install), then be sure the mount command is run before the emerge section below:
If no errors are return then boot should be successfully mounted. Check by running the mount command without any arguments and parsing the output with grep:
mount | grep boot
Ask Portage to install it:
emerge --ask sys-apps/memtest86+
? (question marks) in the file below with correct numbers for the system's boot partition:
title=memtest86+ root (hd?,?) kernel /boot/memtest86plus/memtest
For GRUB2 just run grub-mkconfig. As long as the package has been emerged, a configuration file has already been installed to /etc/grub.d/39_memtest86+:
grub-mkconfig -o /boot/grub/grub.cfg
If GRUB2 was installed with the
multislotUSE flag, use the command grub2-mkconfig instead.
For LILO, add this to the lilo.conf configuration file:
image = /boot/memtest86plus/memtest label = memtest86+
Then rebuild LILO's MBR entry:
Add this to the configuration file:
LABEL memtest86+ MENU LABEL memtest86+ LINUX /boot/memtest86plus/memtest
To use memtest86+ the system needs to be rebooted using the newly added boot item
emerge --ask --unmerge sys-apps/memtest86+
- http://www.pcworld.com/article/232640/memtest86.html - A PCWorld article describing the usefulness and features of memtest86+.