test: store curproc at top of stack

I don't actually think this is worthwhile, but I figured
I would check it in before reverting it, so that it can
be in the revision history.

Pros:
  * curproc doesn't need to turn on/off interrupts
  * scheduler doesn't have to edit curproc anymore

Cons:
  * it's ugly
  * all the stack computation is more complicated.
  * it doesn't actually simplify anything but curproc,
    and even curproc is harder to follow.

1 files changed, 4 insertions, 1 deletions

diff --git a/proc.h b/proc.h
index 2063baa..a2abb82 100644
--- a/proc.h
+++ b/proc.h
@@ -46,6 +46,10 @@ struct proc {
   char name[16];            // Process name (debugging)
 };
 
+// The word at kstack + KSTACKTOP is a pointer to the struct proc.
+#define KSTACKTOP (KSTACKSIZE-4)
+
+
 // Process memory is laid out contiguously, low addresses first:
 //   text
 //   original data and bss
@@ -55,7 +59,6 @@ struct proc {
 // Per-CPU state
 struct cpu {
   uchar apicid;               // Local APIC ID
-  struct proc *curproc;       // Process currently running.
   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