Turns out we didn't end up needing this capability, so, commenting it
out because it is a shy too powerful and is like packing a live
mortar shell in a storage unit: eventually, someone is going to
get hurt, even though it seems mostly harmless at the moment.
Code just commented out in case we need this feature in the future,
but, the main reason it was asked for (the PDDB) was accomplished
without it.
Correctly handle transitions to and from exception handling.
Previously, the thread ID was incorrectly set such that the exception
handler became a valid thread. This has been adjusted so that the
exception handler is no longer considered a thread, and all other
threads will cease scheduling during this process.
Signed-off-by: Sean Cross <sean@xobs.io>
If a process is currently running, it needs to be placed into the
`Debug` state rather than the `Ready` state.
Additionally, the process that's being switched to must enter the
`Running` state.
Signed-off-by: Sean Cross <sean@xobs.io>
Previously, we were creating a stack beginning at the initial page,
and then growing it upwards. The correct behavior is to begin it at
the top and grow it downwards.
In order to do this, subtract the size of the stack from the initial
pointer.
Signed-off-by: Sean Cross <sean@xobs.io>
Since `MemoryRange::new()` is now unsafe, add an `unsafe {}` note when
calling this function on Hosted mode.
This fixes the build.
Signed-off-by: Sean Cross <sean@xobs.io>
This function allows for creating arbitrary memory ranges. Mark this
function as `unsafe` in order to warn users that this can be used to
create invalid memory regions.
Signed-off-by: Sean Cross <sean@xobs.io>
This enables processes to be "suspended" by going into a Debug state.
Messages will back up and processes will continue to be scheduled around
the suspended process, while the system will continue to operate.
Signed-off-by: Sean Cross <sean@xobs.io>
When a process is terminated, we disconnect it from all other processes.
We also need to free the slot in the server table.
Signed-off-by: Sean Cross <sean@xobs.io>
When the kernel is processing an interrupt, use the exception stack.
This ensures that the kernel interrupt handler can switch processes
without having its stack go away.
This is used for debug information.
Signed-off-by: Sean Cross <sean@xobs.io>
Due to several errors, multi-page lending did not work properly.
To begin with, if a page was not allocated then it would not be able to
be sent. That is, if you allocated 8192 bytes but only ever accessed the
first 4096 bytes, then an error would be encountered when lending the
unaccessed upper page.
Furthermore, due to a striding error in accessing pointers, half-pages
were treated as full pages.
Signed-off-by: Sean Cross <sean@xobs.io>
This brings intra-process lending in-line with intra-process sending,
where memory is not remapped the pointer is simply reused.
We may change this at a later point in order to further enforce the
concept of lent-memory-is-inaccessible, so do not rely in this behavior.
Signed-off-by: Sean Cross <sean@xobs.io>
This implements a syscall to shut down a server. Servers may not be shut
down if they have outstanding messages that they have seen but not
responded to.
Signed-off-by: Sean Cross <sean@xobs.io>
When moving memory between processes, update the owner of that page to
match the new PID. Otherwise, memory can never be released.
Signed-off-by: Sean Cross <sean@xobs.io>
The `current_thread` variable is used to determine which thread to
switch back to after a context switch occurs. Keep track of the thread
more closely.
Signed-off-by: Sean Cross <sean@xobs.io>
If we switch to a thread and specify a thread ID, remember that as the
current thread ID.
This prevents thread starvation by repeatedly going back to the same
thread ID.
Signed-off-by: Sean Cross <sean@xobs.io>
This fixes the case where there is only one process active and it tries
to send messages to itself, or it yields to itself.
This closes issue #42.
Signed-off-by: Sean Cross <sean@xobs.io>
the code originally would pick the same thread over and over again
this fix starts the thread search at one plus the current thread
wrapping around to one plus the current thread, so we always try
to pick a new thread compared to the current one, instead of
generally picking the same thread most of the time.
In an effort to homogonize platforms, we are moving away from `usize` in
favour of `u32`. Allow the `CID` type to be a `u32` in the kernel by
casting it to a `usize` as necessary.
Signed-off-by: Sean Cross <sean@xobs.io>
Servers will, by default, get randomly-assigned SIDs. Certain servers
will want to have well-known SIDs, such as the log server or the
nameserver. These will use a separate call in order to perform this
priveledged operation.
A subsequent patch will add `CreateServer`.
Signed-off-by: Sean Cross <sean@xobs.io>
This fixes issues regarding passing memory between processes.
We now properly catch `ReturnMemory` and give the memory back.
Signed-off-by: Sean Cross <sean@xobs.io>
The `sender` was, previously, somewhat mislabeled. It was a combination
of PID and TID, except when it wasn't.
Instead, make this value a combination of ConnectionID and queue index.
This makes it easier to reason about which connection we're responding
to.
Additionally, don't expose teh global Server Index Table to userspace
programs.
Signed-off-by: Sean Cross <sean@xobs.io>
Previously, each process could return one chunk of memory. With this
change, processes can now return one chunk of memory per thread. This
enables multiple threads to lend memory to a server.
Signed-off-by: Sean <xobs@ci.betrusted.io>
Server IDs were being improperly indexed, resulting in a
probably-invalid server index being returned.
Adjust these so that correct server indices are returned.
Signed-off-by: Sean Cross <sean@xobs.io>
Cargo appears to cache packages in the workspace when multiple packages
use the same crate. Unfortunately, Xous uses different features
depending on whether it's running in the kernel or in userspace.
Pull the kernel version of "xous" in under a different namespace in
order to force it to use a different build.
Signed-off-by: Sean Cross <sean@xobs.io>
This package serves only to build tests for the kernel, because the
kernel wants to use a different mechanism for spawning processes.
Cargo doesn't support having `#[cfg(test)]` attributes on modules in
order to allow conditional compilation depending on whether we're
running a test or not. To work around this, `main.rs` is included in
another dummy crate.
Signed-off-by: Sean Cross <sean@xobs.io>
