3 ms·

The paper has some mentions of ECC. https://people.inf.ethz.ch/omutlu/pub/RowPress_isca23.pdf https://people.inf.ethz.ch/omutlu/pub/RowPress_isca23.pdf For ex

The paper has some mentions of ECC. https://people.inf.ethz.ch/omutlu/pub/RowPress_isca23.pdf https://people.inf.ethz.ch/omutlu/pub/RowPress_isca23.pdf For example, the first mention of ECC says this: > we ensure that the tested DRAM modules and chips have neither rank-level nor on-die ECC. Doing so ensures that we directly observe and analyze all circuit-level bitflips without interference from architecture-level correction and mitigation mechanisms. Later in the paper they say: > We examine the capability of ECC, which is widely used in modern memory systems to correct memory errors, in mitigating Row Press. We analyze the number of bitflips in every 64-bit word for both single- and double-sided RowPress for a tAggON of 7.8 Ms. To maximize the number of bitflips at this tAggON, we activate the aggressor row(s) as many times as possible within 60 ms at 80°C. […] > We make two key observations from our analysis. First, there are up to 25 Row Press bitflips (not shown) in a 64-bit data word. ECC schemes that are widely used in memory systems (e.g., SECDED [122] and Chipkill [123-125\23) cannot correct or detect all RowPress bitflips we observe, which can lead to silent data corruption [126- 128]. Even a (7, 4) Hamming code (correcting one bitflip in a 4-bit data word) [122] with 75% DRAM storage overhead (3 parity bits for every 4 data bits), is not capable of correcting 25 bitflips in a 64-bit data word. Other ECC schemes that can correct all Row Press bitflips require prohibitively large storage overheads. Thus, relying on ECC alone to prevent all RowPress bitflips is a very expensive solution. Second, for all three manufacturers (Mfrs. A, B, and C), a significant fraction (up to 0.99%, 35.77%, and 10.08% for tAggON = 7.8 us, respectively) of 64-bit data words exhibit at least three Row-Press bitflips. This makes RowPress bitflips costly to prevent using techniques like memory page retirement (where erroneous DRAM rows are not used in the system) [129, 130] since such techniques could render up to 35.77% of storage capacity useless.

exmadscientist 3y ago
What a thoroughly disingenuous argument they make. Let me rephrase that in terms of adventures trying to break in to the castle throne room. They say that if you keep sending a million adventuring parties, eventually some will break in, perhaps as many as 25 adventurers at once and there's no way you can afford 25 guards 24/7 to protect anything. The obvious counter-argument is that, sure, maybe the millionth party will get in... but someone had to notice the guards stopping the first 999,999 failures, right? That counts for something? Most "defeats" of ECC in these RowHammer style attacks are of this form, and are not in my opinion actually defeats. Authors are just sleazily handwaving away the ECC to get a sexier paper. (ECC with OS error reporting is like having posted guards with someone supervising. If this analogy makes you wonder how things can possibly work without any ECC/guards, congratulations, you see the argument the ECC-everywhere camp are making!)

exmadscientist 3y ago

What a thoroughly disingenuous argument they make. Let me rephrase that in terms of adventures trying to break in to the castle throne room. They say that if you keep sending a million adventuring parties, eventually some will break in, perhaps as many as 25 adventurers at once and there's no way you can afford 25 guards 24/7 to protect anything. The obvious counter-argument is that, sure, maybe the millionth party will get in... but someone had to notice the guards stopping the first 999,999 failures, right? That counts for something? Most "defeats" of ECC in these RowHammer style attacks are of this form, and are not in my opinion actually defeats. Authors are just sleazily handwaving away the ECC to get a sexier paper. (ECC with OS error reporting is like having posted guards with someone supervising. If this analogy makes you wonder how things can possibly work without any ECC/guards, congratulations, you see the argument the ECC-everywhere camp are making!)