ptos/amd64: ps: Add context switching stub

Signed-off-by: Chloe M <chloe@mensia.org>

service/ptos/arch/amd64/ps/context.c

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: MD context management
+ * Author:      Chloe M.
+ */
+
+#include <hal/context.h>
+#include <ex/trace.h>
+
+VOID
+HalContextSwitch(TRAP_FRAME *Frame)
+{
+    TRACE("CONTEXT SWITCHING IS A TODO\n");
+}

service/ptos/arch/amd64/ps/thread.c

@@ -10,6 +10,7 @@
 #include <hal/page.h>
 #include <ps/thread.h>
 #include <machine/gdt.h>
+#include <machine/lapic.h>
 #include <mm/vm.h>
 #include <string.h>
 
@@ -79,3 +80,9 @@ HalThreadInit(THREAD *Thread, ULONG Flags, UPTR Ip)
     ThreadInitTcb(Thread, Tcb, Ip);
     return STATUS_SUCCESS;
 }
+
+VOID
+HalPrimeThreadTimer(ULONG Usec)
+{
+    MdLapicTimerOneshotUs(Usec);
+}