Comment by SomeStupidPoint | Hacker News Reader

Comment by SomeStupidPoint | Hacker News Reader

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SomeStupidPoint

I'm not sure I understand your question, but the one that most pertains to ECC would be preventing corruption of the routine performing the checks --

It varies greatly by the method you use to ECC in software, since they all feature different mechanisms.

In the case of the one I had in mind, the kernel is relatively small (so errors are unlikely), and once loaded, it's stable against bit errors. There are probably better answers, I'm not an expert on software ECC.

(Tampering is a different issue -- if they can tamper with the program, ECC won't save you from them writing garbage to memory. So that a hack which can write memory can bypass memory safety isn't really interesting.)

I meant tampering via a side channel attack (e.g. forcing a bit flip that ecc would protect). It doesn’t matter if your data types have referential integrity if a hacker could disable that protection.

What I am arguing against is saying a typesafe language obviates the need for ecc memory.

> What I am arguing against is saying a typesafe language obviates the need for ecc memory.

Which isn't what anyone said: I claimed you can do ECC in software and that type systems assist with that by making a clean interface and verifying the full implementation. (Since ECC is really just a lift of normal functions.)

There's little difference between using 9 bits in hardware and 9 bits in software, except that you need to cleanly load your ECC code onto CPU cache and you're using CPU instructions per byte loaded. The reason we do ECC in hardware is efficiency on an operation we're doing on literally every byte.

Lots of systems, eg harddrives, use ECC in their actual formats too, because you can do more complex ECC at the software level and not merely the extra bit. Sometimes, this software ECC is more efficient than hardware based ECC would be, because we're okay with less than 12.5% redundancy as long as we can still correct the errors we expect to find.

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