Proof-of-concept RHS library inspired by Expecting the Unexpected - Radiation Hardened Software by Mehlitz and Penix.
Traditional Booleans use a single 1 bit for true and 0 for false.
Additionally, conditionals recognize any value other than 0 as true. This
means than any single bit error in a false variable will change the outcome of
a conditional using that variable. The RHS Boolean in rhsbool.h solves this by
using a full 32 bit value, 0 for false and 0xFFFFFFFF for true. It then
provides two functions: rhs_is_true() and rhs_is_false() which count the
number of 1 bits in the given value. Any value with more than half of the bits
set to 1 is considered true, less than half is false, and exactly half is an
error case that should be handled by the client.
The EDAC memory is edacmemory.h works similarly to smart pointers. It
automatically adds Reed-Solomon error correction to any object, and verifies and
corrects the data when operator* or operator-> are called.
The TMR memory in edacmemory.h is designed to provided redundancy for simple types. By default it keeps three copies of the type, but additional copies can be requested using the template parameter. It compares the three copies on any access and restores the majority.
The RHS library is released in the BDS 3-clause license. However, it also used fec-3.0.1 which is released by Phil Karn under the LGPL.
- Test with larger objects
- Test with random error injection
- Find a way to update the ECC data automatically after non-const access
- Hamming code enums
- GCC plugin to use RHS library automatically, warnings for implicit comparisons in conditionals
- Portable code/constant data scrubber (this violates write protections on modern architectures)