From abf847a083888bbed4260ecacf849ea19f23e810 Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@mit.edu>
Date: Tue, 31 Jan 2017 17:47:16 -0500
Subject: Start of an experiment to remove the use of gs for cpu local
 variables.

---
 lapic.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'lapic.c')

diff --git a/lapic.c b/lapic.c
index 7507f97..9039665 100644
--- a/lapic.c
+++ b/lapic.c
@@ -99,11 +99,11 @@ lapicinit(void)
 }
 
 int
-cpunum(void)
+lapiccpunum(void)
 {
   int apicid, i;
   
-  // Cannot call cpu when interrupts are enabled:
+  // Cannot call cpunum when interrupts are enabled:
   // result not guaranteed to last long enough to be used!
   // Would prefer to panic but even printing is chancy here:
   // almost everything, including cprintf and panic, calls cpu,
@@ -111,7 +111,7 @@ cpunum(void)
   if(readeflags()&FL_IF){
     static int n;
     if(n++ == 0)
-      cprintf("cpu called from %x with interrupts enabled\n",
+      cprintf("cpunum called from %x with interrupts enabled\n",
         __builtin_return_address(0));
   }
 
-- 
cgit v1.2.3


From ed396c068b881877330f7d40bfce02db9b1199b3 Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@mit.edu>
Date: Wed, 1 Feb 2017 18:04:13 -0500
Subject: Eliminate code for gs trick to track per-cpu state.  We rely on
 lapiccpunum() to find a per-cpu id with which we locate a cpu's cpu struct.

---
 lapic.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

(limited to 'lapic.c')

diff --git a/lapic.c b/lapic.c
index 9039665..9a12f17 100644
--- a/lapic.c
+++ b/lapic.c
@@ -98,22 +98,12 @@ lapicinit(void)
   lapicw(TPR, 0);
 }
 
+// Should be called with interrupts disabled: the calling thread shouldn't be
+// rescheduled between reading lapic[ID] and checking against cpu array.
 int
 lapiccpunum(void)
 {
   int apicid, i;
-  
-  // Cannot call cpunum when interrupts are enabled:
-  // result not guaranteed to last long enough to be used!
-  // Would prefer to panic but even printing is chancy here:
-  // almost everything, including cprintf and panic, calls cpu,
-  // often indirectly through acquire and release.
-  if(readeflags()&FL_IF){
-    static int n;
-    if(n++ == 0)
-      cprintf("cpunum called from %x with interrupts enabled\n",
-        __builtin_return_address(0));
-  }
 
   if (!lapic)
     return 0;
-- 
cgit v1.2.3


From c9fa90f7e514f27fa1ac071cd9795f3830ab6a1b Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@mit.edu>
Date: Wed, 1 Feb 2017 20:36:41 -0500
Subject: A tiny bit of clean up (e.g., move code searching cpu array from
 lapic.c into mycpu() in proc.c.

---
 lapic.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

(limited to 'lapic.c')

diff --git a/lapic.c b/lapic.c
index 9a12f17..dc69eb6 100644
--- a/lapic.c
+++ b/lapic.c
@@ -9,7 +9,6 @@
 #include "traps.h"
 #include "mmu.h"
 #include "x86.h"
-#include "proc.h"  // ncpu
 
 // Local APIC registers, divided by 4 for use as uint[] indices.
 #define ID      (0x0020/4)   // ID
@@ -98,22 +97,12 @@ lapicinit(void)
   lapicw(TPR, 0);
 }
 
-// Should be called with interrupts disabled: the calling thread shouldn't be
-// rescheduled between reading lapic[ID] and checking against cpu array.
 int
-lapiccpunum(void)
+lapicid(void)
 {
-  int apicid, i;
-
   if (!lapic)
     return 0;
-
-  apicid = lapic[ID] >> 24;
-  for (i = 0; i < ncpu; ++i) {
-    if (cpus[i].apicid == apicid)
-      return i;
-  }
-  panic("unknown apicid\n");
+  return lapic[ID] >> 24;
 }
 
 // Acknowledge interrupt.
-- 
cgit v1.2.3