qemu_x86: increase to 8MB of RAM

Previously we were instantiating QEMU with 32MB of RAM but
only enabling a small fraction of it.

Now we boot with 8MB of ram. We ignore the first 4K so we can
make that an unmapped paged to catch NULL pointer dereferences.

If XIP is enabled, the "ROM" region will be the first half of
memory, the "RAM" region the latter.

Move the IDT_LIST and MMU_LIST regions elsewhere so they don't
overlap the new memory arrangement.

Use !XIP to fix a problem where CONFIG_RAM_SIZE was set incorrectly
for XIP case.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

arch/x86/soc/ia32/Kconfig.defconfig

@@ -12,17 +12,17 @@ config SOC
 	default ia32
 
 config PHYS_LOAD_ADDR
-	default 0x00100000
+	default 0x00001000
 
 config PHYS_RAM_ADDR
 	default 0x00400000
 
 config RAM_SIZE
-	default 128 if XIP
-	default 256
+	default 4096 if XIP
+	default 8188 if !XIP
 
 config ROM_SIZE
-	default 3072 if XIP
+	default 4092 if XIP
 
 config SYS_CLOCK_HW_CYCLES_PER_SEC
 	default 150000000 if LOAPIC_TIMER

arch/x86/soc/ia32/linker.ld

@@ -38,8 +38,8 @@ MEMORY
      * target. However, it shouldn't overlap any other regions.
      */
 
-    IDT_LIST        : ORIGIN = 2K, LENGTH = 2K
-    MMU_LIST	    : ORIGIN = 4k, LENGTH = 1K
+    IDT_LIST        : ORIGIN = 0xFFFF1000, LENGTH = 2K
+    MMU_LIST	    : ORIGIN = 0xFFFF2000, LENGTH = 1K
     }
 
 #include <arch/x86/linker.ld>

boards/x86/qemu_x86/Makefile.board

@@ -5,7 +5,7 @@ QEMU_BIOS ?= /usr/share/qemu
 QEMU_CPU_TYPE_x86 = qemu32
 QEMU_X86_NO_REBOOT_y =
 QEMU_X86_NO_REBOOT_  = -no-reboot
-QEMU_FLAGS_x86 = -m 32 -cpu $(QEMU_CPU_TYPE_x86) \
+QEMU_FLAGS_x86 = -m 8 -cpu $(QEMU_CPU_TYPE_x86) \
 		$(QEMU_X86_NO_REBOOT_$(CONFIG_REBOOT)) \
 		-nographic -vga none -display none -net none \
 		-clock dynticks -no-acpi -balloon none \