diff --git a/arch/x86/soc/ia32/soc.c b/arch/x86/soc/ia32/soc.c
index 78b0fd4cb03..13c61aacb58 100644
--- a/arch/x86/soc/ia32/soc.c
+++ b/arch/x86/soc/ia32/soc.c
@@ -18,21 +18,19 @@
 #include <device.h>
 #include <init.h>
 #include <mmustructs.h>
+#include <linker/linker-defs.h>
 
 #ifdef CONFIG_X86_MMU
+/* Mark text and rodata as read-only, for XIP rest of flash unmapped */
+MMU_BOOT_REGION((u32_t)&_image_rom_start, (u32_t)&_image_rom_size,
+		MMU_ENTRY_READ);
 
-#ifdef CONFIG_XIP
-MMU_BOOT_REGION(CONFIG_PHYS_LOAD_ADDR, CONFIG_ROM_SIZE*1024, MMU_ENTRY_READ);
+/* From _image_ram_start to the end of all RAM, read/write */
+MMU_BOOT_REGION((u32_t)&_image_ram_start, (u32_t)&_image_ram_all,
+		MMU_ENTRY_WRITE);
 
-MMU_BOOT_REGION(CONFIG_PHYS_RAM_ADDR, CONFIG_RAM_SIZE*1024, MMU_ENTRY_WRITE);
-#else
-MMU_BOOT_REGION(CONFIG_PHYS_LOAD_ADDR, CONFIG_RAM_SIZE*1024, MMU_ENTRY_WRITE);
-#endif /*CONFIG_XIP */
-
-MMU_BOOT_REGION(CONFIG_LOAPIC_BASE_ADDRESS, 4*1024, MMU_ENTRY_WRITE);
-MMU_BOOT_REGION(CONFIG_IOAPIC_BASE_ADDRESS, 1024*1024, MMU_ENTRY_WRITE);
-
-/*HPET */
-MMU_BOOT_REGION(CONFIG_HPET_TIMER_BASE_ADDRESS, 4*1024, MMU_ENTRY_WRITE);
+MMU_BOOT_REGION(CONFIG_LOAPIC_BASE_ADDRESS, KB(4), MMU_ENTRY_WRITE);
+MMU_BOOT_REGION(CONFIG_IOAPIC_BASE_ADDRESS, MB(1), MMU_ENTRY_WRITE);
+MMU_BOOT_REGION(CONFIG_HPET_TIMER_BASE_ADDRESS, KB(4), MMU_ENTRY_WRITE);
 
 #endif /* CONFIG_X86_MMU*/