1// Per-CPU state
2struct cpu {
3 uchar apicid; // Local APIC ID
4 struct context *scheduler; // swtch() here to enter scheduler
5 struct taskstate ts; // Used by x86 to find stack for interrupt
6 struct segdesc gdt[NSEGS]; // x86 global descriptor table
7 volatile uint started; // Has the CPU started?
8 int ncli; // Depth of pushcli nesting.
9 int intena; // Were interrupts enabled before pushcli?
10 struct proc *proc; // The process running on this cpu or null
11};
12
13extern struct cpu cpus[NCPU];
14extern int ncpu;
15
16//PAGEBREAK: 17
17// Saved registers for kernel context switches.
18// Don't need to save all the segment registers (%cs, etc),
19// because they are constant across kernel contexts.
20// Don't need to save %eax, %ecx, %edx, because the
21// x86 convention is that the caller has saved them.
22// Contexts are stored at the bottom of the stack they
23// describe; the stack pointer is the address of the context.
24// The layout of the context matches the layout of the stack in swtch.S
25// at the "Switch stacks" comment. Switch doesn't save eip explicitly,
26// but it is on the stack and allocproc() manipulates it.
27struct context {
28 uint edi;
29 uint esi;
30 uint ebx;
31 uint ebp;
32 uint eip;
33};
34
35enum procstate { UNUSED, EMBRYO, SLEEPING, RUNNABLE, RUNNING, ZOMBIE };
36
37// Per-process state
38struct proc {
39 uint sz; // Size of process memory (bytes)
40 pde_t* pgdir; // Page table
41 char *kstack; // Bottom of kernel stack for this process
42 enum procstate state; // Process state
43 int pid; // Process ID
44 struct proc *parent; // Parent process
45 struct trapframe *tf; // Trap frame for current syscall
46 struct context *context; // swtch() here to run process
47 void *chan; // If non-zero, sleeping on chan
48 int killed; // If non-zero, have been killed
49 struct file *ofile[NOFILE]; // Open files
50 struct inode *cwd; // Current directory
51 char name[16]; // Process name (debugging)
52};
53
54// Process memory is laid out contiguously, low addresses first:
55// text
56// original data and bss
57// fixed-size stack
58// expandable heap
59