replace setjmp/longjmp with swtch

1 files changed, 8 insertions, 8 deletions

diff --git a/proc.h b/proc.h
index 84dc57d..f76e264 100644
--- a/proc.h
+++ b/proc.h
@@ -10,18 +10,18 @@
 // Don't need to save all the %fs etc. segment registers,
 // because they are constant across kernel contexts.
 // Save all the regular registers so we don't need to care
-// which are caller save.
-// Don't save %eax, because that's the return register.
-// The layout of jmpbuf must match code in setjmp.S.
-struct jmpbuf {
+// which are caller save, but not the return register %eax.
+// (Not saving %eax just simplifies the switching code.)
+// The layout of context must match code in swtch.S.
+struct context {
+  int eip;
+  int esp;
   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 };
@@ -38,7 +38,7 @@ struct proc {
   int killed;               // If non-zero, have been killed
   struct file *ofile[NOFILE];  // Open files
   struct inode *cwd;        // Current directory
-  struct jmpbuf jmpbuf;     // Jump here to run process
+  struct context context;   // Switch here to run process
   struct trapframe *tf;     // Trap frame for current interrupt
   char name[16];            // Process name (debugging)
 };
@@ -61,7 +61,7 @@ extern struct proc *curproc[NCPU];  // Current (running) process per CPU
 // Per-CPU state
 struct cpu {
   uchar apicid;               // Local APIC ID
-  struct jmpbuf jmpbuf;       // Jump here to enter scheduler
+  struct context context;     // Switch here to enter scheduler
   struct taskstate ts;        // Used by x86 to find stack for interrupt
   struct segdesc gdt[NSEGS];  // x86 global descriptor table
   char mpstack[MPSTACK];      // Per-CPU startup stack