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// segments in proc->gdt
#define SEG_KCODE 1 // kernel code
#define SEG_KDATA 2 // kernel data+stack
#define SEG_UCODE 3
#define SEG_UDATA 4
#define SEG_TSS 5 // this process's task state
#define NSEGS 6
struct jmpbuf {
// saved registers for kernel context switches
// don't need to save all the fs etc. registers because
// they are constant across kernel contexts
// save all the regular registers so we don't care which are caller save
// don't save eax because that's the return register
// layout known to setjmp.S
int ebx;
int ecx;
int edx;
int esi;
int edi;
int esp;
int ebp;
int eip;
};
enum proc_state { UNUSED, EMBRYO, SLEEPING, RUNNABLE, RUNNING, ZOMBIE };
struct proc{
char *mem; // start of process's memory (a kernel address)
// process memory is laid out contiguously:
// text
// original data and bss
// fixed-size stack
// expandable heap
uint sz; // user memory size
char *kstack; // kernel stack
enum proc_state state;
int pid;
int ppid;
void *chan; // sleep
int killed;
struct fd *fds[NOFILE];
struct inode *cwd;
struct jmpbuf jmpbuf;
struct trapframe *tf; // points into kstack, used to find user regs
};
extern struct proc proc[];
extern struct proc *curproc[NCPU]; // can be NULL if no proc running.
#define MPSTACK 512
struct cpu {
uchar apicid; // Local APIC ID
struct jmpbuf jmpbuf;
struct taskstate ts; // only to give cpu address of kernel stack
struct segdesc gdt[NSEGS];
char mpstack[MPSTACK]; // per-cpu start-up stack
volatile int booted;
int nlock; // # of locks currently held
};
extern struct cpu cpus[NCPU];
extern int ncpu;
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