Requires:

• #16

Enables:

• #45

newlib expects 17 system calls to be defined in order to build. Not all of them need to be functional; for example, we can push back implementation of execve and fork until we actually start thinking about process management.

_exit, write and sbrk should be implemented right away. For the other syscalls, the newlib documentation provides trivial implementations that just return error values; good enough for now?

Requires:

• #22
• #42

rustc can target several different libc implementations. However, newlib is currently unsupported.

Adding support for musl was a week-end project for compiler hacker @alexcrichton. We can add support for newlib by following his example.

Chapter 7.10 of the book has information on the subject.

For demo day.

Rust implements "panics" (equivalent to C++ exceptions). They're used throughout the standard library, including when allocating memory through Box::new.

To support panics, we need to implement ::rt::begin_unwind and possibly ::rt::begin_unwind_fmt. A good first implementation would print to the emergency console and immediately crash.

Enables:

• #33

We got our metaphors wrong, and our STACK_BOTTOM is a higher number than our STACK_TOP.

Two changes:

• Exchange STACK_TOP and STACK_BOTTOM in the .lds linker script
• mov $STACK_TOP, %rbp in start.S

This is a longer-term goal, we still need to agree on a strategy for documenting code.

We should use cargo doc on our code base (see here) and publish the results online.

Necessary to implement device discovery. Chapter 8 of the book.

ELF files have a PT_INTERP section specifying what "interpreter" should be used to run them, if any. The default is usually something like /lib/elf/ld-linux.so.1, but it wouldn't be too hard to point to a script somewhere (/etc/crust/run, for example) which just calls xl create -c /etc/crust/crust.cfg 'name="$(RANDOM_GUID)"' 'kernel="$1"'.

Using __HYPERVISOR_sched_op.

Should print to the emergency console. Not necessarily urgent.

Depends on:

• #49

Supporting libstd would let us take arbitrary Rust code (modulo asm!, #[cfg(target_os = "linux")], etc.) and compile it to run on Crust.

The vast majority of crates (libraries, etc.) in the Rust ecosystem depend on libstd. Users should be able to write programs for Crust that depend on third-party crates.

There's some important functionality in src/xen/arch/x86_64/mem.rs that's slightly sketchy. It'd be good to look it over, and link to resources on the topic where relevant.

start_info_page is currently being passed into main, but that's incompatible with the typical signature for main as int main(int argc, char** argv). It should be made a global variable instead.

Enables: #24

We're almost certainly going to need a cross-compiler targeting something like i686-elf. This page is a good start.

Used by network and block devices.

Enables:

• #15
• #16

Integrating LWIP would allow us to add networking, without implementing all networking ops from scratch. As this is what Mini-OS uses, it appears to be a viable alternative.

Implement virtio driver support.

• Write a simple "Waterfall" allocator
• port the alloc library

Requires:

• #34

VIRQ codes

Before calling main, there are quite a few subsystems we need to initialize. The bootloader in boot/start.S should call a prologue function, which should itself call main after performing initialization.

Would enable the use of cargo test --no-run for unit tests and cargo bench --no-run for benchmarks.

Requires:

• #7

Crust needs heap allocation.

• Do we need virtual memory management? (Likely not)
• What symbols are we expected to provide?
• Actually implement it.

Requires:

• #17

We've already implemented support for printing to the Hypervisor console (also called "debugging console" or "emergency console"), which can be read via xl dmesg. However, it would be nice to support printing to the guest console, if only as a way to provide a meaningful stdout for Crust applications.

Requires:
#22

Rust enums can be represented in memory as either scalar types or as the default representation for C enums on that platform. The latter is almost never correct, and it should be replaced with the appropriate value.

Requires:

• #21
• #28
• #35

Facilitates:

• #15

Enables:

• #20

On one hand, Mini-OS uses some kind of compiler flag voodoo to build Xen images without a cross-compiler. On the other, Newlib's build system is notoriously finicky, and it's usually built with a cross-compiler.

Let's bridge that gap somehow and get Newlib and Mini-OS to compile together into a Xen image.

Enables:

• #15
• #16

Not having a debugger is pretty problematic.

Minimal reproduction on Xen 4.6.0 debug build

xen-devel mailing list thread

Xen's "shared info page" is used to communicate to VMs important information related to concurrency, time-keeping, memory management, and event handling.

Requires:

• #21
• #26
• #35

Facilitates:

• #16

Enables:

• #25

We need to determine what to use for the Stack and Heap size.

Currently, if we extend the size of the heap too much, we get a general protection fault while trying to allocate memory

Big push to make further work more manageable.

Can be done in crust.cfg or as a command line argument to xl by setting the cmdline field (see here).

Used by the console and XenStore. Documented in section 6.7 of the book.

Enables:

• #9
• #26
• #36

Probably Simple File System: see here

Requires:
#15

Xen equivalent to interrupts. Uses __HYPERVISOR_event_channel_op.

Enables:

• #15
• #16

Requires:

• #23