3 ms·
This hardware defect just keeps on giving. Since we're unlikely to see larger memory cells again, mitigations will likely be applied. There is a good question
by niftich 10y ago
This hardware defect just keeps on giving.
Since we're unlikely to see larger memory cells again, mitigations will likely be applied. There is a good question on a discussion board [1] from last year about memory scrambling and its utility here; but with no responses. Can these questions be answered? Some points about memory scrambling are also made here [2] by Kim of the 2014 CMU paper.
[1] https://groups.google.com/forum/#!topic/rowhammer-discuss/tpiC2MeowrM https://groups.google.com/forum/#!topic/rowhammer-discuss/tp...
[2] https://github.com/CMU-SAFARI/rowhammer https://github.com/CMU-SAFARI/rowhammer
- b161023ar 10y agoHmm, so the purpose of memory scrambling is to avoid excessive current swings on the data bus, because they have some kind of undesirable effect on the voltage regulator. I wonder if the result of such current swings is just excessive EMI or power consumption, or if the supply can actually go out of regulation. If you know the scrambling algorithm then you can generate those current swings intentionally...
- userbinator 10y agoI suppose you could get some interesting things to happen if you kick the control loop of the regulator into oscillation and set up some resonance; I wrote an old comment here, related to video cameras, that describes one such experience I had: https://news.ycombinator.com/item?id=9251479 https://news.ycombinator.com/item?id=9251479 It also reminds me of the old CD copy-protection schemes that worked by attempting to (and in a lot of cases, successfully) forcing the scrambling algorithm it uses to output difficult-to-write bit strings: https://www.pricenfees.com/digit-life-archives/magic-figures-detective-story-unreadable-cds https://www.pricenfees.com/digit-life-archives/magic-figures... http://www.cdmediaworld.com/hardware/cdrom/news/0102/sd2_truth.shtml http://www.cdmediaworld.com/hardware/cdrom/news/0102/sd2_tru...
- qb45 10y agoIt seems somebody reversed this Intel scrambler at least to some extent (I only skimmed the article): http://www.sciencedirect.com/science/article/pii/S1742287616300032#sec4 http://www.sciencedirect.com/science/article/pii/S1742287616... They suggest that the scrambler is reseeded randomly on every power up so it may be hard to control raw bits on the data bus.
- deleted 10y ago[deleted]