Deprecate cannon support

[samlaf]

Asked what was the state of cannon support on discord, and was told it was no longer supported:

Feel like this should be better documented in the README. Perhaps the cannon build code should be removed (last commit is 2 years old)? Also maybe describe what's the state of cannon-rs and future plans regarding asterisc vs cannon-rs.

Is the point that the cannon code in the monorepo has a bunch of golang related elf changes (in the patcher) which doesn't work with rust code, hence why cannon-rs was started?

[clabby]

Cannon support is in a bit of a weird spot. We do not have any plans to use it in production, but testing that kona can compile to the target is nice to ensure we can be compatible.

I'll think about this a bit.

p.s., we use a custom target. Rust does only have a supported built-in target for r6, but we specify an r1 target.

[samlaf]

@clabby oh interesting pretty sure I saw a link to mips r2 somewhere, maybe in op-program or cannon documentation itself?

[tynes]

It would be really nice to be able to compile kona down to mips64 to remove asterisc from the hot path of getting kona to prod, but its still a lot of work validating that its production ready

[clabby]

@clabby oh interesting pretty sure I saw a link to mips r2 somewhere, maybe in op-program or cannon documentation itself?

Yeah cannon is an impl of a mips{32/64}r2 processor. We run on a stricter target, but r2 processors should be backwards compatible w/ r1 programs.

Glad to revisit this in the future if we decide we never want to use cannon, closing as not planned for now :)