Task #
A Task capability represents a schedulable object which may receive CPU time, i.e. a thread or process. A schedulable Task has an associated VSpace, CSpace, IPC buffer, and stores its registers and other state.
Operations #
Task::CONFIGURE #
Configures a task’s associated CSpace, VSpace, and IPC buffer address. The caller must ensure that the provided IPC buffer address is mapped into the appropriate VSpace.
Parameters #
| Register | Details |
|---|---|
| r0 | IPC buffer virtual address |
Capabilities #
| CSlot | Usage | Type | Details |
|---|---|---|---|
| 0 | In | CSpace | CSpace to assign to this task |
| 1 | In | VSpace | VSpace to assign to this task |
Results #
| Error code | Meaning |
|---|---|
| NONE | Success |
| INVALID_PARAM | IPC buffer address is not page-aligned |
| INVALID_PARAM | IPC buffer is not mapped in the given VSpace |
Task::READ_REGISTERS #
TODO
Task::WRITE_REGISTERS #
Writes the registers associated with this task. The task must be in a suspended or unconfigured state before invoking this operation.
Parameters #
The layout of the CPU context structure is arch-specific.
| Register | Details |
|---|---|
| r0 | Pointer to CPU context struct |
Capabilities #
This operation accepts no capabilities.
Results #
| Error code | Meaning |
|---|---|
| NONE | Success |
| INVALID_PARAM | The provided context structure is not mapped in the caller’s VSpace |
Task::READ_TLS_BASE #
TODO
Task::WRITE_TLS_BASE #
Writes the arch-specific TLS base register. The task must be in a suspended or unconfigured state before invoking this operation.
Parameters #
The meaning and usage of the TLS base register is arch-specific and subject to userspace policy.
| Register | Details |
|---|---|
| r0 | Value of the TLS base register |
Capabilities #
This operation accepts no capabilities.
Results #
| Error code | Meaning |
|---|---|
| NONE | Success |
Task::SET_FAULT #
Configures the endpoint for reporting faults from this task. See the faults page for further details.
Parameters #
This operation accepts no parameters.
Capabilities #
| CSlot | Usage | Type | Details |
|---|---|---|---|
| 0 | In | Endpoint | Fault endpoint |
Results #
| Error code | Meaning |
|---|---|
| NONE | Success |
| INVALID_CTYPE | The provided capability is not an endpoint |
| INVALID_CSLOT | The invoked task already has a fault handler |
Task::RESET_FAULT #
Removes the configured fault endpoint from this task, if any.
Parameters #
This operation accepts no parameters.
Capabilities #
This operation accepts no capabilities.
Results #
This operation always succeeds.
| Error code | Meaning |
|---|---|
| NONE | Success |
Task::SUSPEND #
Suspends this task, causing it to be ineligible for further scheduling. The task is guaranteed to be suspended before this operation completes, even if it is currently running on another core.
Parameters #
This operation accepts no parameters.
Capabilities #
This operation accepts no capabilities.
Results #
This operation always succeeds.
| Error code | Meaning |
|---|---|
| NONE | Success |
Task::RESUME #
Resumes this task, making it eligible to be scheduled at an unspecified point in the future. Note that tasks are only scheduled if they have been configured with an appropriate VSpace, CSpace, and IPC buffer; otherwise this function will have no effect (the task will instead be resumed as soon as the appropriate configure call is made).
Parameters #
This operation accepts no parameters.
Capabilities #
This operation accepts no capabilities.
Results #
This operation always succeeds.
| Error code | Meaning |
|---|---|
| NONE | Success |