Re-defining components/modules and their relationship

[bokdeuk-jeong]

There are ongoing discussions about how to define ISLET RMM components and where to place them. Let's start discussing it here.

[bitboom]

Background

The role of current modules is below.

• armv9a: Architecture dependent code & data structure
• monitor: Architecture independent code & data structure

The main purpose of this dependency is what makes monitor independently for reusability.

Problem

But monitor has highly dependent with arm architecture. So, this dependency makes overabundant code writing.
If we write architecture related code, we have to declare Trait to monitor & implement it to armv9a.

The examples are smc & realm.

armv9a/src  $ tree -L 2 realm/
realm/
├── context.rs
├── mm
│   ├── mod.rs
│   ├── page.rs
│   ├── page_table
│   ├── stage2_translation.rs
│   ├── stage2_tte.rs
│   └── translation_granule_4k.rs
├── mod.rs
├── registry.rs
├── timer.rs
└── vcpu.rs

Suggestion

• armv9a: Architecture dependent data structure (Register, asm) like aarch64-cpu
• monitor: RMM dependent code & data structure

My suggestion is that move code of armv9a to monitor except for data structure like registers.
The reason is that i want to focus 'monitor' as implementation of RMM.
Furthermore i want to change armv9a to aarch64-cpu.

Final goal

After re-organization, i want to talk about trusted/untrusted code. I think tock design is good reference.

[zpzigi754]

Now, I got your point. I agree with the intention of merging the previous monitor and armv9a as one, because there are so many unnecessary traits which are used just for circumventing the original dependency (e.g., calling armv9a's functions from monitor). I think that traits should be used for the common interface not just for the single implementation like now.

In terms of the suggestion, I thought the inverse direction (== moving monitor's code into armv9a and renaming armv9a as monitor or something else). Either direction would be fine, as long as the two modules get merged.

[bitboom]

I thought the inverse direction (== moving monitor's code into armv9a and renaming armv9a as monitor or something else).

It's more convenient way! I could try this way 😄