3 ms·

I was curious if there is any indication of vulnerability between Rowhammer attacks and running Memtest86, a procedure I've been doing on new builds for many ye

by dave7 7y ago

I was curious if there is any indication of vulnerability between Rowhammer attacks and running Memtest86, a procedure I've been doing on new builds for many years, and it's a program that IIRC tests for all sorts of RAM issues (usually just being plain faulty) by looking for bit flips. Turns out they do test for Rowhammer vulnerability, though I am not expert enough to know how thorough this may be: > Test 13 - Hammer Test: > Starting from MemTest86 v6.2, potentially two passes of row hammer testing are performed. On the first pass, address pairs are hammered at the highest possible rate. If errors are detected on the first pass, errors are not immediately reported and a second pass is started. In this pass, address pairs are hammered at a lower rate deemed as the worst case scenario by memory vendors (200K accesses per 64ms). If errors are also detected in this pass, the errors are reported to the user as normal. However, if only the first pass produces an error, a warning message is instead displayed to the user. https://www.memtest86.com/technical.htm https://www.memtest86.com/technical.htm

iforgotpassword 7y ago
Ugh, I just realized memtest86 is now closed source proprietary software. While the old open source variant is still for download and memtest86+ exists it doesn't seem to be active anymore.
- striking 7y ago
  Does it need to be active? Have there been significant advancements in the realm of RAM testing?
  - iforgotpassword 7y ago
    Well, testing for rowhammer would be one thing that comes to mind ;-) Also the change log explicitly mentioned support for individual CPU generations (and the last release was 2013) though I don't know how relevant that is or whether it's just cosmetics. Also phrases like "better timings detection" makes you wonder whether updates for newer types of memory are required.
  - loeg 7y ago
    The open memtest86+ doesn't boot from EFI, which is a significant drawback.
    - iforgotpassword 7y ago
      Right, it took me a while to figure that out half a year ago. Didn't realize bios was set to efi only and memtest wouldn't boot from USB. I wonder if that would require a major rewrite or if it's mostly just writing new bootstrap code. Since it's 32 bit code with PAE it's doing funky things like relocating itself at runtime to access more than 4 GB of ram.

by dave7 7y ago

iforgotpassword 7y ago

Ugh, I just realized memtest86 is now closed source proprietary software. While the old open source variant is still for download and memtest86+ exists it doesn't seem to be active anymore.

striking 7y ago
Does it need to be active? Have there been significant advancements in the realm of RAM testing?
- iforgotpassword 7y ago
  Well, testing for rowhammer would be one thing that comes to mind ;-) Also the change log explicitly mentioned support for individual CPU generations (and the last release was 2013) though I don't know how relevant that is or whether it's just cosmetics. Also phrases like "better timings detection" makes you wonder whether updates for newer types of memory are required.
- loeg 7y ago
  The open memtest86+ doesn't boot from EFI, which is a significant drawback.
  - iforgotpassword 7y ago
    Right, it took me a while to figure that out half a year ago. Didn't realize bios was set to efi only and memtest wouldn't boot from USB. I wonder if that would require a major rewrite or if it's mostly just writing new bootstrap code. Since it's 32 bit code with PAE it's doing funky things like relocating itself at runtime to access more than 4 GB of ram.