m1x/x86_64: Load global descriptor table

Signed-off-by: Ian Moffett <ian@mirocom.org>

src/m1x/arch/x86_64/Makefile

@@ -22,6 +22,7 @@ CFLAGS = 				\
 	-D_KERNEL			\
 	-I../../target/		\
 	-I../../include/	\
+	-I../../../sdk/include/
 
 .PHONY: all
 all: $(OFILES) $(ASMOFILES)

src/m1x/arch/x86_64/cpu/cpu_init.c

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2026, Mirocom Laboratories
+ * Provided under the BSD-3 clause
+ */
+
+#include <stdint.h>
+
+/* From cpu/locore.S */
+extern void md_cpu_lgdt(void *gdtr);
+extern char g_GDTR[];
+
+void
+hal_cpu_init(void)
+{
+    /* Load the GDT */
+    md_cpu_lgdt(g_GDTR);
+}

src/m1x/arch/x86_64/cpu/locore.S

@@ -16,6 +16,7 @@ _start:
 1:  hlt
     jmp 1b
 
+    .globl md_cpu_lgdt
 md_cpu_lgdt:
     push %r12
     push %r13

src/m1x/include/hal/cpu.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2026, Mirocom Laboratories
+ * Provided under the BSD-3 clause
+ */
+
+#ifndef _HAL_CPU_H_
+#define _HAL_CPU_H_ 1
+
+/*
+ * Initialize the current processor
+ */
+void hal_cpu_init(void);
+
+#endif  /* !_HAL_CPU_H_ */

src/m1x/kern/kern_init.c

@@ -4,6 +4,7 @@
  */
 
 #include <dev/cons/cons.h>
+#include <hal/cpu.h>
 
 void
 kmain(void)
@@ -11,5 +12,8 @@ kmain(void)
     /* Initialize the console */
     cons_init();
 
+    /* Initialize the BSP */
+    hal_cpu_init();
+
     for (;;);
 }