Port to the x86 Architecture

[ioanaculic]

Pull Request Overview

This pull request fixes the #4171:

• removes the external dependency to the x86 crate
• replaces the x86 structures using tock-registers
• fixes some lints

Testing Strategy

This pull request was tested by @ioanaculic.

TODO or Help Wanted

Rebase and feeback.

I would like to get some feedback before I rebase this.

Documentation Updated

• Updated the relevant files in /docs, or no updates are required.

Formatting

• Ran make prepush.

[bradjc]

This is awesome!!

Note, I haven't reviewed any of the code, but the general directory structure looks good to me.

[alevy]

@reynoldsbd et al, are you able to maybe take a look at this? In particular, you might have the ability to test functional correctness with a downstream with more functionality elsewhere.

In general, my sense is that this looks like what we would want upstream, and if it otherwise smells right (basically works and doesn't have soundness etc issues), we should merge and fix functional issues as they arise (potentially as downstream users find them when moving to this implementation).

[reynoldsbd]

This is awesome, thanks so much @ioanaculic for taking this closer to the finish line! :)

This all looks sensible on first glance. My team is doing some internal validation as well to make sure this all continues to work on our platforms. I'll follow up once we have some results to share. cc @alevy

One last topic: Apart from the x86 dependency, it's not immediately clear to me whether any of the other feedback or pending opens from the original PR have been addressed in this new PR. There was some good feedback over there and I'd hate for it to slip through the cracks. It'd also be nice to have the original PR description copied over to this one; I personally place high value on leaving a good trail in Git history, but I recognize that's not a top priority for everyone.

[lschuermann]

We've discussed this briefly on the core call today.

@reynoldsbd It seems like this already includes all of the other changes which you made on the original PR in response to feedback, and is a strict superset of the commits of that PR.

Therefore, it seems easiest to reference back to #4171, perhaps take some of the original PR's description and feedback integrate it into this one, and finally push this new PR over the finish line.

One of our remaining concerns is around testing these changes, especially running userspace applications, and testing the memory protection implementation. One thing that could allow us to better test these changes is if you could provide a small dummy / test application (either in source or binary form), with instructions on how to load it?

This all looks sensible on first glance. My team is doing some internal validation as well to make sure this all continues to work on our platforms. I'll follow up once we have some results to share. cc @alevy

It's great to hear that you're testing these changes internally. We'd thus holding off on merging this for a couple more days, and can use that time to gather more reviews generally.

[bradjc]

We need to document how to get qemu. The getting started guide doesn't actually include those instructions.

[reynoldsbd]

Good news, we confirmed this is all running smoothly on real silicon!

@HMiyaziwala has opened a PR in the libtock-rs repo to add support for x86. That should allow you to use one of the example apps for testing.

[ioanaculic]

We need to document how to get qemu. The getting started guide doesn't actually include those instructions.

Done.

[alevy]

Apart from my and @bradjc's comments, I think this is good to go.

[alevy]

I'm sorry, this really should be the last thing, IMO, but I added some suggested changes necessary for the documentation to compile. I can't apply those myself since I don't have push access to the branch.

[ioanaculic]

I'm sorry, this really should be the last thing, IMO, but I added some suggested changes necessary for the documentation to compile. I can't apply those myself since I don't have push access to the branch.

Thank you. I commited all the suggestions.

[ppannuto]

A more 'skim' of a review; deferring largely to the this being working code and a foundation

Literally wrong button :(

[ppannuto]

Actually hitting the 'Approve' radio button this time 😬