Switch kernel stack and move boot structures initialization into separate routine

xtoskrnl/ke/amd64/krnlinit.c

@@ -0,0 +1,48 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/ke/amd64/krnlinit.c
+ * DESCRIPTION:     CPU architecture specific kernel initialization
+ * DEVELOPERS:      Rafal Kupiec <belliash@codingworkshop.eu.org>
+ */
+
+#include <xtos.h>
+
+
+/**
+ * This routine starts up the XT kernel. It is called after switching boot stack.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+KepStartKernel(VOID)
+{
+    LdrPrint(L"Hello from new kernel stack!\n");
+    for(;;);
+}
+
+/**
+ * Switches to a new kernel boot stack.
+ *
+ * @return This routine does not return any value
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+KepSwitchBootStack(IN ULONG_PTR Stack)
+{
+    /* Discard old stack frame, switch stack and jump to KepStartKernel() */
+    asm volatile("mov %0, %%rdx\n"
+                 "xor %%rbp, %%rbp\n"
+                 "mov %%rdx, %%rsp\n"
+                 "sub %1, %%rsp\n"
+                 "jmp KepStartKernel\n"
+                 :
+                 : "m" (Stack),
+                   "i" (FLOATING_SAVE_AREA_SIZE | KEXCEPTION_FRAME_SIZE | KSWITCH_FRAME_SIZE),
+                   "p" (KepStartKernel));
+}