Not 1:1 mapping

apps/u6_demo.c

@@ -13,10 +13,13 @@ char intro[] =
             "3: Execute Kernel code\r\n"
             "4: Write own code\r\n"
             "5: Stackoverflow\r\n"
-            "6: read undefined memeory\r\n";
+            "6: read undefined memeory\r\n"
+            "7: Access Sram that was mapped to undef (abort)\r\n"
+            "8: Access Undef (abort) that was mapped to sram\r\n";
 
 __attribute__ ((section (".usertext"))) int brick_it() {
-    for (int i = 0; i < 190; ++i)
+    while (1) {
+    for (int i = 0; i < 287; ++i)
         sys_debug_put_char(intro[i]);
     volatile u32 test;
     switch (sys_debug_get_char()) {
@@ -56,7 +59,14 @@ __attribute__ ((section (".usertext"))) int brick_it() {
             );
             break;
         case '6':
-            test = *((u32*) UNDEF_MEMORY1 + 200);
+            test = *((u32*) (UNDEF_MEMORY1 + MEGABYTE + 200));
             break;
+        case '7':
+            test = *((u32*) (EXTERNAL_SRAM + 17*MEGABYTE));
+            break;
+        case '8':
+            test = *((u32*) (UNDEF_MEMORY1));
+            break;
+    }
     }
 }
\ No newline at end of file

boards/portux/board.h

@@ -7,6 +7,8 @@
 
 #define INTERNAL_SRAM    0x200000
 
+#define MEGABYTE         0x100000
+
 #define EXTERNAL_SRAM  0x20000000
 #define PROCESS_STACKS 0x20200000
 #define UNDEF_MEMORY1  0x90000000

boards/portux/drivers/mmu.c

@@ -21,6 +21,8 @@ void init_first_level_pagetable() {
     for (uint i = 0; i < 63; ++i) {
         l1table.desc[userland_desc + 1 + i] |= (AP_RW_RW << 10);
     }
+    l1table.desc[(EXTERNAL_SRAM + 17*MEGABYTE) >> 20] = (UNDEF_MEMORY1) | (AP_RW_RW << 10) | 0b10;
+    l1table.desc[(UNDEF_MEMORY1) >> 20] = (EXTERNAL_SRAM + 17*MEGABYTE) | (AP_RW_RW << 10) | 0b10;
 }
 
 void init_mmu() {