metta-systems/vesper

Single-address-space capability-based nanokernel

vesper's Issues

Reach parity with old unsorted branch

Steps:

• cargo build --build-std
• enable testing infrastructure
  • run qemu semihosting tests on gh actions
• init BSS
• switch from EL3/EL2 to EL1
• bump some obsolete dependencies
• add license check
• init MMU
• init memory types and map correctly
• init exception handling, handle traps
• add mailbox interface
  • add BumpAllocator
  • add DMA_ALLOCATOR
• add FrameBuffer interface
• add gpio
• run serial test with probe-rs and merge JTAG configuration before merging UART code - probe not functioning with cortex-a/bcm
• add UART serial
  • add miniUart
  • add PL011 Uart
• find out why core::fmt::num::imp::fmt_u64 crashes somewhere in the stack (only before MMU is enabled)
  • this is due to use of ldrh/strh on an unaligned storage (perf optimization in DEC_DIGITS_LUT use)
• add JTAG debug helpers (see if anything additional for probe-rs support is needed)
  • add SEGGER RTT interface using rtt-target crate -- postponed in feature/add-rtt branch, current situation with RTT support on the host side is pretty bad. - see #35 for follow up.
• add graphical Display
• add console with kernel command interface
• add Power management
• add working GitPod workspace (at least Edit, Build and Run tests in QEMU)
• transfer documentation to appropriate places -- see #36 for follow up.

Add kernel syscall API and ABI

1. Add user-space thread which would call a syscall,
2. Parse syscall ABI arguments and call kernel API function,
3. Parse API function result and return appropriate response via ABI to user space.

Explore: Add DTB parsing support

See https://github.com/metta-systems/vesper/tree/explore/parse-dtb

• Parse DTB structures and properly detect necessary hardware
  • Interrupt controller
  • Memory size
  • Serial ports locations and types (??)

Evaluate Profile-Guided Optimization (PGO)

Hi!

Recently I checked Profile-Guided Optimization (PGO) improvements on multiple projects. The results are here. The most interesting to Vesper results probably are PGO results on operating systems (Linux kernel and Windows): https://github.com/zamazan4ik/awesome-pgo#operating-systems

We need to perform PGO benchmarks on Vesper. And if it shows improvements - add a note about possible improvements in Vesper performance with PGO. Providing an easier way (e.g. a build option) to build scripts with PGO can be useful for the end-users too. I think this kind of optimization can be useful for the project since if PGO will be able to optimize somehow CPU workload of the operating system, we can potentially reduce requirements for the hardware and possibly decrease power consumption.

For the Rust projects, I suggest trying to start with cargo-pgo.

Here you can find different materials about PGO: benchmarks in different software, examples of how PGO is already integrated with different projects, PGO support in multiple compilers, and some PGO-related pieces of advice.

Dependabot couldn't fetch the branch/reference for cortex-a

Your dependency file specified a branch or reference for cortex-a, but Dependabot couldn't find it at the project's source. Has it been removed?

View the update logs.

Transfer documentation to appropriate places

Collect docs from doc/ folder in the old tree and spread it into blog, docs and notes.

Explore: Use of GATs

See here and discussion here.

Enable higher-half kernel with TTBR1

Remap kernel immediately from EL2/EL3 before going to EL1, this is simplest.
Pre-fill mapping tables using ttt tool.

Map kernel and init_thread space and enable MMU

• map kernel through TTBR1 and full phys-mem access
• map init_thread through minimal page directory mappings and set of boot capabilities to the rest of physmem
• enable MMU

Add serial boot

• Add just boot target to build and boot through tftp or serial interface (see example in rust-raspberrypi-OS-tutorials' uart-chainloader)

Explore: Advanced MMU management

See https://github.com/metta-systems/vesper/tree/explore/mmu-and-allocation

• Implement full abstractions and API to manipulate MMU pages

Build `chainofcommand` on windows

Currently CI fails because termion cannot be build on windows.

This dependency can be made optional, I suspect.

Specify kernel API surface

• Low-level calls
• Kernel object types
• Capability-based calls

Explore: Add interrupt controller (ARM GICv3)

See https://github.com/metta-systems/vesper/tree/explore/interrupt-control

• Add support for generic interrupts support on RPi3 and ARM GIC support on RPi4.

MMU: enable aarch64 mmu with identity paging

• Must have working framebuffer (properly cached)
• Must clean up TLB etc
• Must use type-system limits in addressing different page levels (similar to phil-opp tutorial)

Add SEGGER RTT interface using `rtt-target` crate

See https://github.com/metta-systems/vesper/tree/explore/jlink-rtt

• postponed in feature/add-rtt branch, current situation with RTT support on the host side is pretty bad.

Rename asm! to llvm_asm!

Recent rust-lang change rust-lang/rust#68404 deprecated asm! - rename it to llvm_asm! to avoid breakage.