Memtest86

MemTest86 and Memtest86+ are memory test software programs designed to test and stress test an x86 architecture computer's random-access memory (RAM) for errors, by writing test patterns to most memory addresses, reading back the data, and comparing for errors.[5] Each tries to verify that the RAM will accept and correctly retain arbitrary patterns of data written to it, that there are no errors where different bits of memory interact, and that there are no conflicts between memory addresses.

MemTest86
Developer(s)Chris Brady and PassMark Software
Initial release1994 (1994)[1]
Stable release
10.4 (Build 1000)[2] / 20 April 2023 (2023-04-20)
Written inC and assembly
TypeUtility
LicenseProprietary software
Websitewww.memtest86.com
Memtest86+
Developer(s)Samuel Demeulemeester and Martin Whitaker
Initial releaseearly 2004 (2004)[3]
Stable release
v6.20[4] Edit this on Wikidata / 7 May 2023
Repositorygithub.com/memtest86plus/memtest86plus
Written inC and assembly
TypeUtility
LicenseGPL-2.0-only
Websitewww.memtest.org

History

MemTest86 was developed by Chris Brady in 1994.[1] It was written in C and x86 assembly, and for all BIOS versions, was released under the GNU General Public License (GPL). The bootloading code was originally derived from Linux 1.2.1.[6] The program is compiled as position-independent code so as to be able to move itself around and test all the memory regions.[7]

After MemTest86 remained at version 3.0 (2002 release) for two years, Samuel Demeulemeester created the Memtest86+ fork to add support for newer CPUs and chipsets. As of May 2023 the latest version of Memtest86+ is 6.20.[8][3] Both versions now support current multi-core processors, the corresponding chipsets, and UEFI.[8][3]

Starting from MemTest86 2.3 and Memtest86+ 1.60, the program can output a list of bad RAM regions in the format expected by the BadRAM patch for the Linux kernel.[9][10] GRUB2 is able to supply this same information to an unpatched kernel, making the BadRAM patch unnecessary.[11] Microsoft Windows has a similar feature (badmemorylist/badmemoryaccess), but manual conversion is required for setting it up.[12]

PassMark purchase

In February 2013, the original MemTest86 was sold to PassMark. The BIOS version was updated under GPL until version 4.3.7. By then the feature set of the two forks were approximately equal.[1]

MemTest86 Version 5.0 (3 December 2013) was rewritten for UEFI booting, allowing for secure boot approval and mouse support. All UEFI versions are released under a proprietary freeware license. When UEFI is not available, Version 5.0 (and later) fall back to BIOS booting and loads the old version 4.3.7. Version 6.0.0 (13 Feb 2015) adds support for DDR4 RAM, and a row-hammer test based on research from Yoongu Kim, et al..[9][13][1] Version 10 states only UEFI boot and will not boot on non-UEFI systems, requiring separate download of the older 4.3.7 version which is also maintained on the official website downloads for that purpose.

MemTest86+

The BIOS-based line of MemTest86+ entered a stall after the release of version 5.01 (September 2013). In April 2020, the final BIOS-based version, 5.31 beta, was released with a short changelog claiming "many fixes".[14]

In May 2020, Martin Whitaker forked MemTest86+ 5.31 into "PCMemTest", rewriting it for UEFI support, DDR4 and DDR5 RAM, and supporting all current AMD and Intel chipsets and CPUs. In October 2022, this branch merged back, becoming MemTest86+ 6.0.[15][16]

Features
Detections of faulty memory are displayed prominently. The application shows which memory locations failed and which patterns made them fail.

There are two development streams of Memtest86. The original is simply known as MemTest86. The other, known as Memtest86+, is a development fork of the original MemTest86. Their on-screen appearance and functionality were almost identical up until the v4 releases. However, version 5 of MemTest86 added a mouse-driven graphical user interface (GUI) and UEFI support.

These programs work with nearly all PC-compatible computers from 80386- and 80486-based systems to the latest systems with 64-bit processors. Each new release adds support for newer processors and chipsets.[9][10]

MemTest86(+) is designed to run as a stand-alone, self-contained program from a bootable USB flash drive, CD-ROM, floppy disk, or from a suitable boot manager without an operating system present.[17] This is because the program must directly control the hardware being tested and leave as much of the RAM space as possible for examination.

MemTest86(+)'s testing is very comprehensive, so it can find otherwise hidden problems on machines that appear to work normally.[17][18] With many chipsets, MemTest86 allows counting of failures even in error-correcting ECC DRAM (without special handling, error correcting memory circuits can mask problems with the underlying memory chips).

Some errors manifest intermittently or depend on the precise bits being stored, and do not occur on each pass; such errors may be revealed by running many passes over an extended period. Some tests use different data each pass to reveal data-dependent errors.[19]

Adoption

MemTest86+ is a part of many Linux distributions, including Debian, the derived Ubuntu, and Arch Linux.[20] Ubuntu includes it as part of the default installation if the machine is booting in BIOS mode; it is available from the GRUB OS-select menu.[21] Whilst Memtest86+ version 5.01 required significant patching by distributions to keep the 2013 code base functional,[22] the 6.0 release did not require such extensive patching.[23]

References
  1. "MemTest86 History". MemTest86.com. Archived from the original on 2019-05-11. Retrieved 2018-02-09.
  2. "PassMark MemTest86 - Version History".
  3. "Memtest86+ History". Memtest.org.
  4. "Memtest86+ release v6.20". 7 May 2023.
  5. "MemTest86 Technical Information". MemTest86.com. PassMark Software. Retrieved 2015-10-22.
  6. "bootsect.S - chromiumos/third_party/memtest - Git at Google". ChromiumOS Source. Copyright (C) 1991, 1992 Linus Torvalds 1-Jan-96 Modified by Chris Brady
  7. "README.build-process - chromiumos/third_party/memtest - Git at Google". chromium.googlesource.com.
  8. "MemTest86 Support". MemTest86.com.
  9. "PassMark MemTest86 - Version History".
  10. "Memtest86+ - Advanced Memory Diagnostic Tool".
  11. "GNU GRUB Manual 1.99 § Badram".
  12. "How to block out or map out bad RAM in Windows..." thecomputerperson. 20 April 2015. Retrieved 19 May 2019.
  13. Kim, Yoongu; Daly, Ross; Kim, Jeremie; Fallin, Chris; Lee, Ji Hye; Lee, Donghyuk; Wilkerson, Chris; Lai, Konrad; Mutlu, Onur (2014-07-08). "Flipping Bits in Memory Without Accessing Them: An Experimental Study of DRAM Disturbance Errors" (PDF). Carnegie Mellon University. Retrieved 2015-04-07.
  14. "Memtest86+ Archives". Memtest86+.; "728766 – sys-apps/memtest86+-5.31b version bump". bugs.gentoo.org.
  15. Klotz, Aaron (2022-10-24). "Memtest86+ Is Back! New Version Released After 9 Years". Tom's Hardware. Retrieved 2022-10-25.
  16. "memtest86+ v6.0 Released As Rewritten Open-Source RAM Tester". www.phoronix.com. Retrieved 2022-10-25.
  17. Fisher, Tim (2018-02-06). "MemTest86 v7.5 Free Memory Testing Tool Review". Lifewire. Dotdash. Retrieved 2018-02-24.
  18. "MemTest86 Technical Information: Algorithms". MemTest86.com. PassMark Software. Retrieved 2014-11-01.
  19. "MemTest86 Technical Information: Detailed Descriptions". MemTest86.com. PassMark Software. Retrieved 2015-10-22.
  20. "Arch Linux - memtest86+ 5.01-3 (any)". Retrieved 7 April 2019.
  21. "MemoryTest". Ubuntu Help Wiki. Retrieved 7 April 2019. Hold down Shift to bring up the GRUB menu. Use the arrow keys to move to the entry labeled Ubuntu, memtest86+
  22. "Patch tracker: memtest86+". Debian Sources. Retrieved 20 September 2023.
  23. "Patch tracker: memtest86+". Debian Sources. Retrieved 20 September 2023.
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