Struct TaskContext 

#[repr(C)]
pub struct TaskContext {

    pub sp: u64,
    pub r19: u64,
    pub r20: u64,
    pub r21: u64,
    pub r22: u64,
    pub r23: u64,
    pub r24: u64,
    pub r25: u64,
    pub r26: u64,
    pub r27: u64,
    pub r28: u64,
    pub r29: u64,
    pub lr: u64,
    pub tpidr_el0: u64,
}

Saved hardware states of a task.

The context usually includes:

• Callee-saved registers
• Stack pointer register
• Thread pointer register (for kernel-space thread-local storage)
• FP/SIMD registers

On context switch, current task saves its context from CPU to memory, and the next task restores its context from memory to CPU.

Fields

sp: u64

r19: u64

r20: u64

r21: u64

r22: u64

r23: u64

r24: u64

r25: u64

r26: u64

r27: u64

r28: u64

r29: u64

lr: u64

tpidr_el0: u64

Thread Pointer

Implementations

impl TaskContext

pub fn new() -> TaskContext

Creates a dummy context for a new task.

Note the context is not initialized, it will be filled by switch_to (for initial tasks) and init (for regular tasks) methods.

pub fn init(&mut self, entry: usize, kstack_top: VirtAddr, tls_area: VirtAddr)

Initializes the context for a new task, with the given entry point and kernel stack.

pub fn switch_to(&mut self, next_ctx: &TaskContext)

Switches to another task.

It first saves the current task’s context from CPU to this place, and then restores the next task’s context from next_ctx to CPU.

Trait Implementations

impl Debug for TaskContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for TaskContext

fn default() -> TaskContext

Returns the “default value” for a type.