- no swapping of kernel pages
- mark L1 PT's properly in the memory allocation table
(was accidentally marking them with the VA of the first address
allocated)
instead of sending scalar messages on every page alloc/free, which
is a lot of traffic, introduce an API where the swapper can request
a snapshot of the alloc status by mapping the kernel's alloc
table as a read-only structure into the swapper's memory space,
and then invoking the swapper in its interrupt context to read that out.
The structure is unmapped on return from the context.
additionally, a running tally of free space is now maintained
and this can be queried with a fast syscall.
Thus, the normal workflow is the swapper would have a timer that
periodically queries the kernel's free space level, and when it
falls below a critical amount, it will invoke the expensive snapshot.
this can also be extended so that the kernel can call into
the swapper's interrupt context with a "help, OOM imminent"
message down the road.
DUe to https://github.com/rust-lang/rust/issues/114447 direct access to
static mut variables causes a warning which will be turned into an
error in the 2024 edition.
The workaround is to use `addr_of!()` and `addr_of_mut!()` macros and
then dereference that.
Signed-off-by: Sean Cross <sean@xobs.io>
With Rust 1.76.0, we no longer support building with `#![no_std]` or
`panic = "abort"`, both of which are required within the kernel. As a
workaround, go back to building the kernel under
`riscv32imac-unknown-none-elf`.
Signed-off-by: Sean Cross <sean@xobs.io>
Support passing process arguments in register 2 as part of arguments to
a process.
This requires updating the `InitialProcess` struct that is received from
the loader, and so requires modeifications to be made in tandem.
Signed-off-by: Sean Cross <sean@xobs.io>
The phys_to_virt function can be used to determine what physical address
page is mapped to a virtual address page.
This throws an error when a page is mapped twice, which shouldn't
happen.
Signed-off-by: Sean Cross <sean@xobs.io>
The kernel stack offset should be aligned to 16 bytes. Previously it was
aligned to 8 bytes. It's unclear if this was the cause of any issues,
but it is best practice to keep things aligned to 16 bytes.
As part of this, key the atomic instructions off of the CPP macro
presence of atomic instructions.
Signed-off-by: Sean Cross <sean@xobs.io>
