Most of the changes introduced in this commit were rolled back,
but, there is now a test facility that's hanging out for the PDDB
to help with future debug efforts.
The patch was motivated by a problem observed in FSCB consistency
when it's updated. Ultimately the root cause was traced to a
cache coherence problem and it's fixed by a patch in the spinor
crate.
However, this patch still retains a check that the data is coherent,
in case the flushing routine isn't complete or some other factor
was missed. It also includes a large amount of commented-out code
that keeps a bit of history used to debug the problem -- eventually,
we can just cull that but it's kept around in case we got the
root cause wrong (or there were multiple causes and coherence is
just one of them).
This will allow for e.g. xous on riscv32-imac but not a precursor
target, for example: by using feature selectors we get to have
a bigger range of targets that we support, such as for implementations
that haven't been upstreamed or have official target-triples.
The downsides are:
- patch override libraries don't absorb feature flags. so, for
example, the AES crate that is used to patch other crates won't
be aware of the target features without modifying the referencing
crates.
- features are normally meant to be additive, but target features
are mutually exclusive. The mutex is enforced by a check in
utralib that throws a panic on build if two targets are accidentally
selected at the same time.
This adds some UX feedback in the edge case that a suspend could not
happen due to a blocking sever, e.g. a sha512 hash pending or
a SPINOR flash write/erase pending.
The UI will tell the user to retry again; usually the ops in
a normally functioning system for hashes or SPI are very short,
so we could almost just retry automatically but I think for now
I want to see if this edge case actually happens.
somehow, on windows builds, this doesn't break; but when building
under linux, the kernel config difference matters. Now that I
know how to pass features down, let's do it right.
