Cycle through multiple tasks in multiple processes

zion/scheduler/process.cpp

@@ -1,6 +1,8 @@
 #include "scheduler/process.h"
 
 #include "debug/debug.h"
+#include "memory/paging_util.h"
+#include "memory/physical_memory.h"
 #include "scheduler/scheduler.h"
 #include "scheduler/thread.h"
 
@@ -23,17 +25,28 @@ Process* Process::RootProcess() {
   return proc;
 }
 
+Process::Process() : id_(gNextId++) {
+  cr3_ = phys_mem::AllocatePage();
+  InitializePml4(cr3_);
+  CreateThread();
+}
+
 void Process::CreateThread() {
   Thread* thread = new Thread(this, next_thread_id_++);
-
-  ThreadEntry* entry = thread_list_front_;
-  while (entry->next != nullptr) {
-    entry = entry->next;
-  }
-  entry->next = new ThreadEntry{
+  ThreadEntry* tentry = new ThreadEntry{
       .thread = thread,
       .next = nullptr,
   };
+
+  if (thread_list_front_ == nullptr) {
+    thread_list_front_ = tentry;
+  } else {
+    ThreadEntry* entry = thread_list_front_;
+    while (entry->next != nullptr) {
+      entry = entry->next;
+    }
+    entry->next = tentry;
+  }
   sched::EnqueueThread(thread);
 }
 

zion/scheduler/scheduler.cpp

@@ -77,7 +77,9 @@ class Scheduler {
     Thread* prev = current_thread_;
     current_thread_ = current_thread_->next_thread_;
     prev->next_thread_ = nullptr;
-    Enqueue(prev);
+    if (prev->pid() != 0) {
+      Enqueue(prev);
+    }
     context_switch(prev->Rsp0Ptr(), current_thread_->Rsp0Ptr());
 
     asm volatile("sti");

zion/scheduler/thread.cpp

@@ -8,9 +8,8 @@ namespace {
 
 extern "C" void thread_init() {
   asm("sti");
-  dbgln("New Thread!");
-  sched::Yield();
-  panic("End of thread.");
+  sched::CurrentThread().Init();
+  panic("Reached end of thread.");
 }
 
 }  // namespace
@@ -32,3 +31,10 @@ Thread::Thread(Process* proc, uint64_t tid) : process_(proc), id_(tid) {
 }
 
 uint64_t Thread::pid() { return process_->id(); }
+
+void Thread::Init() {
+  while (true) {
+    dbgln("[%u.%u]", pid(), id_);
+    sched::Yield();
+  }
+}

zion/scheduler/thread.h

@@ -18,6 +18,9 @@ class Thread {
 
   uint64_t* Rsp0Ptr() { return &rsp0_; }
 
+  // Called the first time the thread starts up.
+  void Init();
+
   // FIXME: Probably make this private.
   Thread* next_thread_;