Since I am the Memory Guy I hate learning that I missed something new and cool in the world of memories, but somehow I was unaware of last week’s Memsys conference in Washington DC until a participant notified me on Saturday that his paper: “Reverse Engineering of DRAMs: Row Hammer with Crosshair,” had been given the the best paper award.
Upon looking at the Memsys website it looks like a very intriguing academic conference. about sixty papers were presented in eight interesting sessions:
- Issues in High Performance Computing
- Nonvolatile Main Memories and DRAM Caches, Parts I & II
- Hybrid Memory Cube and Alternative DRAM Channels
- Thinking Outside the Box
- Improving the DRAM Device Architecture
- Issues and Interconnects for 2.5D and 3D Packaging
- Some Amazingly Cool Physical Experiments
in addition to a few apparently-fascinating keynotes.
Fortunately, all of the papers are Continue reading
One of those nasty little secrets about DRAM is that bits may get corrupted by simply reading the bits in a different part of the chip. This has been given the name “Row Hammer” (or Rowhammer) because repeated accesses to a single one of the DRAM’s internal “rows” of bits can bleed charge off of the adjacent rows, causing bits to flip. These repeated accesses are referred to as “hammering”.
Although this was once thought to be an issue only with DDR3 DRAMs, recent papers (listed on the DDR Detective) show that DDR4 also suffers from Row Hammer issues, even though DRAM makers took pains to prevent it.
One big champion of this phenomenon is Barbara Aichinger (pictured) of FuturePlus Systems, a test equipment maker that specializes in detecting row hammer issues. The Memory Guy has had the pleasure of talking with her about this issue and learning first-hand the kind of difficulties it creates.
How does Row Hammer work? It stems from the fact Continue reading