MMU: Fixed massive problem in assumption of RAM layout

This caused certain addreses which where not RAM memory to be assigned
to virtual addresses incorrectly. This caused a significant slowdown
when running it with KVM due to constantly having to exit the VM if the
OS writes to memory that is not RAM.

This fix increased the performance of KVM significantly and improved TCG
performance.

1 files changed, 5 insertions, 7 deletions

diff --git a/kernel/drivers/pit.c b/kernel/drivers/pit.c
index 30fd3ed..41c0d2a 100644
--- a/kernel/drivers/pit.c
+++ b/kernel/drivers/pit.c
@@ -44,16 +44,14 @@ void set_pit_count(u16 _hertz) {
 }
 
 void int_clock(reg_t *regs) {
-  EOI(0x20);
-  pit_counter++;
-  if (pit_counter * 1000 >= hertz) {
-    pit_counter = 0;
-    clock_num_ms_ticks += 1000 / hertz;
-  }
+  clock_num_ms_ticks++;
   switch_counter++;
-  if (switch_counter * 500 >= hertz) {
+  if (switch_counter >= hertz) {
+    EOI(0x20);
     switch_counter = 0;
     switch_task();
+  } else {
+    EOI(0x20);
   }
 }