Add a new pc access function to get the architectural PC: on CHERI this is not what is in the PC register because the architectural PC is the offset of PCC and the PC register stores the absolute PC (at present -- may review this decision in future). This allows fix for AUIPC and RVFI reported PC.

Disable mmio devices (clint and htif interfaces) when using RVFI to prevent divergence when using TestRIG.

Fix an issue where zeros function defined in sail conflicted with lem builtin (lem backend does not do z encoding) and add default get_config_print_xxx builtins mappings to lem build (now there is no longer a sail definition of the function because of -Oconstant_fold bug). Also remove FEATURE_IMPLICITS ifdef that was required for backwards compatibility with long obsolete sail versions.

os-boot: Update Hafnium image

Move the get_config_ print defaults to the backend preludes, since it seems to get optimized out by sail, making the emulator the command-line options ineffective.

* Reduce the size of the image by removing unused secondary VMs.
* Recompile Linux with -march=rv64imac -mabi=lp64 (softfloat).
* Remove NFS filesystem in Linux as it's not needed.

Add an instruction limit option to C emulator. Also print kips every 2**20 (~100k) instructions with -p option so you can keep see how it varies during execution.

Rename zeros and ones implicit functions to something that sail monomorphisation pass recognises. We don't need the overload.

Can have unintended consequences, due to how overloading interacts
with casts. For example, x : X == y : X can be interpreted as
eq_string(cast(x), cast(y)) if x and y are both castable to string,
even when there is an equality function (X, X) -> bool. Sail->SMT
can't handle strings very well so it's best to just ensure that this
can never occur.

Rather than implicitly casting in logging statements like:

print("xyz" ^ x  ^ " foo " ^ y)

it's now

print("xyz" ^ to_str(x) ^ " foo " ^ to_str(y))

which ensures that the conversion to strings only happens where
intended. I also added a warning to Sail itself to try to catch these
cases in future.

Zero extend rather than sign extend rvfi-dii reports (usefull for 32 …

Zero extend rather than sign extend rvfi-dii reports (usefull for 32 rvfi-dii comparisons where upper bits are not expected to have information in them)

Fixes for get_perf.py script: fix name of tests directory and cope with uc-p test being so fast the script it takes zero microseconds.

Add a bootable Hafnium image

This image includes:
- BBL
- Hafnium Hypervisor
- initrd
  - Linux as a Primary VM
  - Linux as a secondary VM
  - Busybox
  - Hafnium.ko device driver

It runs on Spike, and requires PMP, CLINT and HTIF