the original rather unsafe version is replaced with a more readable
version that has a number of safety checks applied.
in the process of doing this, we now support merging of multiple
argument regions and a variable number of tags to merge.
tested to work on at least the base case of one swap region to
merge into the list.
this is a fairly complicated bit of legacy code that we're
trying to make slightly better/more readable.
some docs are added, as well as getting rid of a bunch of
"magic" constants, instead preferring to map things into
structured data where possible.
also fixed the location of the heap allocation relative to
the boot flow. It's now in a spot where I think we can
safely put dynamically allocated kernel arguments.
The loader grew a lot of hair over the past few months as it
was abused as a baremetal environment for chip bring-up.
A baremetal environment was explicitly created to help with that,
so we don't have to pollute the loader with lots of unused features
and ancilliary code.
Furthermore, a decision was made to eliminate updates from the
loader code base - the loader is just for setting up Xous. This
allows the loader to be more platform-agnostic.
Boot1 instead contains all the platform-specific code for doing updates.
For completeness, we note that boot0 is a minimal piece of code that is the
first step in the chain of trust and is intended to be a read-only
segment of code that has public keys baked into it that are used
to bootstrap the rest of the ecosystem.
At this point, the loader is now slimmed down and runs. Still needs
testing to make sure the culling wasn't too aggressive, but I am
much happier with where this is landing as the loader is once again
just focused on getting Xous up and running.
The code base had evolved through several code names, interim
names, company names and chip names that alternatively did or did
not exist.
Baochip is the definitive name of the company, and the Baochip1x
(full part number BAO1X2S4F-WA) is the definitivey part number of
the SoC. For convenience, the part number is shortened to 'bao1x'
in most feature flags and variable references.
This commit fixes all of the odd names and removes some unmaintained
early targets.
primarily modify the loading method to mark pages with A/D flags
as needed to work around lack of A/D handling in the trap handler
of Xous.
Also inside main.rs is a todo list for polishing off the vex-ii
port and turning into something actually sustainable for Denarius
once we have more of a full SoC model available.
the switch based on target is now absorbed into the new() function.
This paves the way for us to add more CSR ranges into the global
configuration object, i.e. IRQ csrs for I2C.
add a note about the dirty flag - it's not "dead" per se, I
think it is helpful to leave a bread crumb for future hw revs
that might have hardware-enforced dirty bit setting on the PTE.
