Some monitor/mwait stuff I don't use yet..

39064a18 · Silas Boyd-Wickizer · 84ad98da · 39064a18 · 39064a18
--- a/include/bits.hh
+++ b/include/bits.hh
@@ -77,3 +77,11 @@
 #define PERF_SEL_INT        (1ULL << 20)
 #define PERF_SEL_ENABLE     (1ULL << 22)
 #define PERF_SEL_INV        (1ULL << 23)
+
+// CPUID function 0x00000001
+#define CPUID_FEATURES      0x00000001
+#define FEATURE_ECX_MWAIT   (1 << 3)
+
+// CPUID function 0x00000005
+#define CPUID_MWAIT         0x00000005
+
--- a/kernel/idle.cc
+++ b/kernel/idle.cc
@@ -9,6 +9,7 @@
 #include "wq.hh"
 #include "uwq.hh"
 #include "kmtrace.hh"
+#include "bits.hh"

 struct idle {
  struct proc *cur;
@@ -109,7 +110,7 @@ idleloop(void)
          p = proc::alloc();
          if (p == nullptr)
            break;
-          snprintf(p->name, sizeof(p->name), "idleh_%u", mycpu()->id);          
+          snprintf(p->name, sizeof(p->name), "idle_%u", mycpu()->id);          
          p->cpuid = mycpu()->id;
          p->cpu_pin = 1;
          p->context->rip = (u64)idleheir;
@@ -137,6 +138,17 @@ initidle(void)
  if (!p)
    panic("initidle proc::alloc");

+  if (myid() == mpbcpu()) {
+    u32 eax, ebx, ecx;
+    cpuid(CPUID_FEATURES, nullptr, nullptr, &ecx, nullptr);
+    if (ecx & FEATURE_ECX_MWAIT) {
+      // Check smallest and largest line sizes
+      cpuid(CPUID_MWAIT, &eax, &ebx, nullptr, nullptr);
+      assert((u16)eax == 0x40);
+      assert((u16)ebx == 0x40);
+    }
+  }
+  
  SLIST_INIT(&idlem[myid()].zombies);
  initlock(&idlem[myid()].lock, "idle_lock", LOCKSTAT_IDLE);