Merge branch 'master' into sam460ex

* U-Boot Copy arch_mmu.cpp to arch/ppc/ as stubs to fix the build.

src/system/boot/platform/u-boot/Jamfile

@@ -51,7 +51,6 @@ KernelMergeObject boot_platform_u-boot_common.o :
 	cpu.cpp
 	uimage.cpp
 	video.cpp
-	mmu.cpp
 	fdt_support.cpp
 	$(genericPlatformSources)
 	$(libFDTSources)

src/system/boot/platform/u-boot/arch/arm/Jamfile

@@ -12,7 +12,7 @@ KernelMergeObject boot_platform_u-boot_arm.o :
 	# must come first to have _start_* at correct locations
 	shell.S
 
-	#arch_mmu.cpp
+	arch_mmu.cpp
 	#arch_cpu_asm.S
 	arch_start_kernel.S
 	arch_cpu.cpp

src/system/boot/platform/u-boot/arch/ppc/Jamfile

@@ -12,7 +12,7 @@ KernelMergeObject boot_platform_u-boot_ppc.o :
 	# must come first to have _start_* at correct locations
 	shell.S
 
-	#arch_mmu.cpp
+	arch_mmu.cpp
 	arch_cpu_asm.S
 	arch_start_kernel.S
 	arch_cpu.cpp
@@ -20,5 +20,5 @@ KernelMergeObject boot_platform_u-boot_ppc.o :
 	: -fno-pic
 ;
 
-SEARCH on [ FGristFiles arch_cpu_asm.S arch_mmu.cpp ]
+SEARCH on [ FGristFiles arch_cpu_asm.S ]
     = [ FDirName $(HAIKU_TOP) src system kernel arch $(TARGET_ARCH) ] ;

src/system/boot/platform/u-boot/arch/ppc/arch_mmu.cpp

@@ -0,0 +1,707 @@
+/*
+ * Copyright 2004-2008, Axel Dörfler, [email protected].
+ * Based on code written by Travis Geiselbrecht for NewOS.
+ *
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include "mmu.h"
+
+#include <boot/platform.h>
+#include <boot/stdio.h>
+#include <boot/kernel_args.h>
+#include <boot/stage2.h>
+#include <arch/cpu.h>
+#include <arch_kernel.h>
+#ifdef __ARM__
+#include <arm_mmu.h>
+#endif
+#include <kernel.h>
+
+#include <board_config.h>
+
+#include <OS.h>
+
+#include <string.h>
+
+
+//#define TRACE_MMU
+#ifdef TRACE_MMU
+#	define TRACE(x) dprintf x
+#else
+#	define TRACE(x) ;
+#endif
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#define TRACE_MEMORY_MAP
+	// Define this to print the memory map to serial debug,
+	// You also need to define ENABLE_SERIAL in serial.cpp
+	// for output to work.
+
+#ifdef __ARM__
+
+
+/*
+TODO:
+	-recycle bit!
+*/
+
+/*!	The (physical) memory layout of the boot loader is currently as follows:
+	 0x00000000			u-boot (run from NOR flash)
+	 0xa0000000			u-boot stuff like kernel arguments afaik
+	 0xa0100000 - 0xa0ffffff	boot.tgz (up to 15MB probably never needed so big...)
+	 0xa1000000 - 0xa1ffffff	pagetables
+	 0xa2000000 - ?			code (up to 1MB)
+	 0xa2100000			boot loader heap / free physical memory
+
+	The kernel is mapped at KERNEL_BASE, all other stuff mapped by the
+	loader (kernel args, modules, driver settings, ...) comes after
+	0x80020000 which means that there is currently only 2 MB reserved for
+	the kernel itself (see kMaxKernelSize).
+*/
+
+
+/*
+*defines a block in memory
+*/
+struct memblock {
+	const char name[16];
+		// the name will be used for debugging etc later perhaps...
+	addr_t	start;
+		// start of the block
+	addr_t	end;
+		// end of the block
+	uint32	flags;
+		// which flags should be applied (device/normal etc..)
+};
+
+
+static struct memblock LOADER_MEMORYMAP[] = {
+	{
+		"devices",
+		DEVICE_BASE,
+		DEVICE_BASE + DEVICE_SIZE - 1,
+		MMU_L2_FLAG_B,
+	},
+	{
+		"RAM_loader", // 1MB loader
+		SDRAM_BASE + 0,
+		SDRAM_BASE + 0x0fffff,
+		MMU_L2_FLAG_C,
+	},
+	{
+		"RAM_pt", // Page Table 1MB
+		SDRAM_BASE + 0x100000,
+		SDRAM_BASE + 0x1FFFFF,
+		MMU_L2_FLAG_C,
+	},
+	{
+		"RAM_free", // 16MB free RAM (more but we don't map it automaticaly)
+		SDRAM_BASE + 0x0200000,
+		SDRAM_BASE + 0x11FFFFF,
+		MMU_L2_FLAG_C,
+	},
+	{
+		"RAM_stack", // stack
+		SDRAM_BASE + 0x1200000,
+		SDRAM_BASE + 0x2000000,
+		MMU_L2_FLAG_C,
+	},
+	{
+		"RAM_initrd", // stack
+		SDRAM_BASE + 0x2000000,
+		SDRAM_BASE + 0x2500000,
+		MMU_L2_FLAG_C,
+	},
+
+#ifdef FB_BASE
+	{
+		"framebuffer", // 2MB framebuffer ram
+		FB_BASE,
+		FB_BASE + FB_SIZE - 1,
+		MMU_L2_FLAG_AP_RW|MMU_L2_FLAG_C,
+	},
+#endif
+};
+
+
+//static const uint32 kDefaultPageTableFlags = MMU_FLAG_READWRITE;
+	// not cached not buffered, R/W
+static const size_t kMaxKernelSize = 0x200000;		// 2 MB for the kernel
+
+static addr_t sNextPhysicalAddress = 0; //will be set by mmu_init
+static addr_t sNextVirtualAddress = KERNEL_BASE + kMaxKernelSize;
+static addr_t sMaxVirtualAddress = KERNEL_BASE + kMaxKernelSize;
+
+static addr_t sNextPageTableAddress = 0;
+//the page directory is in front of the pagetable
+static uint32 kPageTableRegionEnd = 0;
+
+// working page directory and page table
+static uint32 *sPageDirectory = 0 ;
+//page directory has to be on a multiple of 16MB for
+//some arm processors
+
+
+static addr_t
+get_next_virtual_address(size_t size)
+{
+	addr_t address = sNextVirtualAddress;
+	sNextVirtualAddress += size;
+
+	return address;
+}
+
+
+static addr_t
+get_next_virtual_address_alligned (size_t size, uint32 mask)
+{
+	addr_t address = (sNextVirtualAddress) & mask;
+	sNextVirtualAddress = address + size;
+
+	return address;
+}
+
+
+static addr_t
+get_next_physical_address(size_t size)
+{
+	addr_t address = sNextPhysicalAddress;
+	sNextPhysicalAddress += size;
+
+	return address;
+}
+
+
+static addr_t
+get_next_physical_address_alligned(size_t size, uint32 mask)
+{
+	addr_t address = sNextPhysicalAddress & mask;
+	sNextPhysicalAddress = address + size;
+
+	return address;
+}
+
+
+static addr_t
+get_next_virtual_page(size_t pagesize)
+{
+	return get_next_virtual_address_alligned(pagesize, 0xffffffc0);
+}
+
+
+static addr_t
+get_next_physical_page(size_t pagesize)
+{
+	return get_next_physical_address_alligned(pagesize, 0xffffffc0);
+}
+
+
+/*
+ * Set translation table base
+ */
+void
+mmu_set_TTBR(uint32 ttb)
+{
+	ttb &= 0xffffc000;
+	asm volatile("MCR p15, 0, %[adr], c2, c0, 0"::[adr] "r" (ttb));
+}
+
+
+/*
+ * Flush the TLB
+ */
+void
+mmu_flush_TLB()
+{
+	uint32 value = 0;
+	asm volatile("MCR p15, 0, %[c8format], c8, c7, 0"::[c8format] "r" (value));
+}
+
+
+/*
+ * Read MMU Control Register
+ */
+uint32
+mmu_read_C1()
+{
+	uint32 controlReg = 0;
+	asm volatile("MRC p15, 0, %[c1out], c1, c0, 0":[c1out] "=r" (controlReg));
+	return controlReg;
+}
+
+
+/*
+ * Write MMU Control Register
+ */
+void
+mmu_write_C1(uint32 value)
+{
+	asm volatile("MCR p15, 0, %[c1in], c1, c0, 0"::[c1in] "r" (value));
+}
+
+
+void
+mmu_write_DACR(uint32 value)
+{
+	asm volatile("MCR p15, 0, %[c1in], c3, c0, 0"::[c1in] "r" (value));
+}
+
+
+static uint32 *
+get_next_page_table(uint32 type)
+{
+	TRACE(("get_next_page_table, sNextPageTableAddress %p, kPageTableRegionEnd "
+		"%p, type 0x" B_PRIX32 "\n", sNextPageTableAddress,
+		kPageTableRegionEnd, type));
+
+	size_t size = 0;
+	switch(type) {
+		case MMU_L1_TYPE_COARSE:
+		default:
+			size = 1024;
+			break;
+		case MMU_L1_TYPE_FINE:
+			size = 4096;
+			break;
+		case MMU_L1_TYPE_SECTION:
+			size = 16384;
+			break;
+	}
+
+	addr_t address = sNextPageTableAddress;
+	if (address >= kPageTableRegionEnd) {
+		TRACE(("outside of pagetableregion!\n"));
+		return (uint32 *)get_next_physical_address_alligned(size, 0xffffffc0);
+	}
+
+	sNextPageTableAddress += size;
+	return (uint32 *)address;
+}
+
+
+void
+init_page_directory()
+{
+	TRACE(("init_page_directory\n"));
+	uint32 smalltype;
+
+	// see if subpages disabled
+	if (mmu_read_C1() & (1<<23))
+		smalltype = MMU_L2_TYPE_SMALLNEW;
+	else
+		smalltype = MMU_L2_TYPE_SMALLEXT;
+
+	gKernelArgs.arch_args.phys_pgdir = (uint32)sPageDirectory;
+
+	// clear out the pgdir
+	for (uint32 i = 0; i < 4096; i++)
+	sPageDirectory[i] = 0;
+
+	uint32 *pageTable = NULL;
+	for (uint32 i = 0; i < ARRAY_SIZE(LOADER_MEMORYMAP);i++) {
+
+		pageTable = get_next_page_table(MMU_L1_TYPE_COARSE);
+		TRACE(("BLOCK: %s START: %lx END %lx\n", LOADER_MEMORYMAP[i].name,
+			LOADER_MEMORYMAP[i].start, LOADER_MEMORYMAP[i].end));
+		addr_t pos = LOADER_MEMORYMAP[i].start;
+
+		int c = 0;
+		while (pos < LOADER_MEMORYMAP[i].end) {
+			pageTable[c] = pos |  LOADER_MEMORYMAP[i].flags | smalltype;
+
+			c++;
+			if (c > 255) { // we filled a pagetable => we need a new one
+				// there is 1MB per pagetable so:
+				sPageDirectory[VADDR_TO_PDENT(pos)]
+					= (uint32)pageTable | MMU_L1_TYPE_COARSE;
+				pageTable = get_next_page_table(MMU_L1_TYPE_COARSE);
+				c = 0;
+			}
+
+			pos += B_PAGE_SIZE;
+		}
+
+		if (c > 0) {
+			sPageDirectory[VADDR_TO_PDENT(pos)]
+				= (uint32)pageTable | MMU_L1_TYPE_COARSE;
+		}
+	}
+
+	mmu_flush_TLB();
+
+	/* set up the translation table base */
+	mmu_set_TTBR((uint32)sPageDirectory);
+
+	mmu_flush_TLB();
+
+	/* set up the domain access register */
+	mmu_write_DACR(0xFFFFFFFF);
+
+	/* turn on the mmu */
+	mmu_write_C1(mmu_read_C1() | 0x1);
+}
+
+
+/*!     Adds a new page table for the specified base address */
+static void
+add_page_table(addr_t base)
+{
+	TRACE(("add_page_table(base = %p)\n", (void *)base));
+
+	// Get new page table and clear it out
+	uint32 *pageTable = get_next_page_table(MMU_L1_TYPE_COARSE);
+/*
+	if (pageTable > (uint32 *)(8 * 1024 * 1024)) {
+		panic("tried to add page table beyond the indentity mapped 8 MB "
+			"region\n");
+	}
+*/
+	for (int32 i = 0; i < 256; i++)
+		pageTable[i] = 0;
+
+	// put the new page table into the page directory
+	sPageDirectory[VADDR_TO_PDENT(base)]
+		= (uint32)pageTable | MMU_L1_TYPE_COARSE;
+}
+
+
+/*!	Creates an entry to map the specified virtualAddress to the given
+	physicalAddress.
+	If the mapping goes beyond the current page table, it will allocate
+	a new one. If it cannot map the requested page, it panics.
+*/
+static void
+map_page(addr_t virtualAddress, addr_t physicalAddress, uint32 flags)
+{
+	TRACE(("map_page: vaddr 0x%lx, paddr 0x%lx\n", virtualAddress,
+		physicalAddress));
+
+	if (virtualAddress < KERNEL_BASE) {
+		panic("map_page: asked to map invalid page %p!\n",
+			(void *)virtualAddress);
+	}
+
+	if (virtualAddress >= sMaxVirtualAddress) {
+		// we need to add a new page table
+		add_page_table(sMaxVirtualAddress);
+		sMaxVirtualAddress += B_PAGE_SIZE * 256;
+
+		if (virtualAddress >= sMaxVirtualAddress) {
+			panic("map_page: asked to map a page to %p\n",
+				(void *)virtualAddress);
+		}
+	}
+
+	physicalAddress &= ~(B_PAGE_SIZE - 1);
+
+	// map the page to the correct page table
+	uint32 *pageTable
+		= (uint32 *)(sPageDirectory[VADDR_TO_PDENT(virtualAddress)]
+			& ARM_PDE_ADDRESS_MASK);
+
+	TRACE(("map_page: pageTable 0x%lx\n",
+		sPageDirectory[VADDR_TO_PDENT(virtualAddress)] & ARM_PDE_ADDRESS_MASK));
+
+	if (pageTable == NULL) {
+		add_page_table(virtualAddress);
+		pageTable = (uint32 *)(sPageDirectory[VADDR_TO_PDENT(virtualAddress)]
+			& ARM_PDE_ADDRESS_MASK);
+	}
+
+	uint32 tableEntry = VADDR_TO_PTENT(virtualAddress);
+
+	TRACE(("map_page: inserting pageTable %p, tableEntry %ld, physicalAddress "
+		"%p\n", pageTable, tableEntry, physicalAddress));
+
+	pageTable[tableEntry] = physicalAddress | flags;
+
+	mmu_flush_TLB();
+
+	TRACE(("map_page: done\n"));
+}
+
+
+//	#pragma mark -
+
+
+extern "C" addr_t
+mmu_map_physical_memory(addr_t physicalAddress, size_t size, uint32 flags)
+{
+	addr_t address = sNextVirtualAddress;
+	addr_t pageOffset = physicalAddress & (B_PAGE_SIZE - 1);
+
+	physicalAddress -= pageOffset;
+
+	for (addr_t offset = 0; offset < size; offset += B_PAGE_SIZE) {
+		map_page(get_next_virtual_page(B_PAGE_SIZE), physicalAddress + offset,
+			flags);
+	}
+
+	return address + pageOffset;
+}
+
+
+static void
+unmap_page(addr_t virtualAddress)
+{
+	TRACE(("unmap_page(virtualAddress = %p)\n", (void *)virtualAddress));
+
+	if (virtualAddress < KERNEL_BASE) {
+		panic("unmap_page: asked to unmap invalid page %p!\n",
+			(void *)virtualAddress);
+	}
+
+	// unmap the page from the correct page table
+	uint32 *pageTable
+		= (uint32 *)(sPageDirectory[VADDR_TO_PDENT(virtualAddress)]
+			& ARM_PDE_ADDRESS_MASK);
+
+	pageTable[VADDR_TO_PTENT(virtualAddress)] = 0;
+
+	mmu_flush_TLB();
+}
+
+
+extern "C" void *
+mmu_allocate(void *virtualAddress, size_t size)
+{
+	TRACE(("mmu_allocate: requested vaddr: %p, next free vaddr: 0x%lx, size: "
+		"%ld\n", virtualAddress, sNextVirtualAddress, size));
+
+	size = (size + B_PAGE_SIZE - 1) / B_PAGE_SIZE;
+		// get number of pages to map
+
+	if (virtualAddress != NULL) {
+		// This special path is almost only useful for loading the
+		// kernel into memory; it will only allow you to map the
+		// 'kMaxKernelSize' bytes following the kernel base address.
+		// Also, it won't check for already mapped addresses, so
+		// you better know why you are here :)
+		addr_t address = (addr_t)virtualAddress;
+
+		// is the address within the valid range?
+		if (address < KERNEL_BASE
+			|| address + size >= KERNEL_BASE + kMaxKernelSize) {
+			TRACE(("mmu_allocate in illegal range\n address: %lx"
+				"  KERNELBASE: %lx KERNEL_BASE + kMaxKernelSize: %lx"
+				"  address + size : %lx \n", (uint32)address, KERNEL_BASE,
+				KERNEL_BASE + kMaxKernelSize, (uint32)(address + size)));
+			return NULL;
+		}
+		for (uint32 i = 0; i < size; i++) {
+			map_page(address, get_next_physical_page(B_PAGE_SIZE),
+				kDefaultPageFlags);
+			address += B_PAGE_SIZE;
+		}
+
+		return virtualAddress;
+	}
+
+	void *address = (void *)sNextVirtualAddress;
+
+	for (uint32 i = 0; i < size; i++) {
+		map_page(get_next_virtual_page(B_PAGE_SIZE),
+			get_next_physical_page(B_PAGE_SIZE), kDefaultPageFlags);
+	}
+
+	return address;
+}
+
+
+/*!	This will unmap the allocated chunk of memory from the virtual
+	address space. It might not actually free memory (as its implementation
+	is very simple), but it might.
+*/
+extern "C" void
+mmu_free(void *virtualAddress, size_t size)
+{
+	TRACE(("mmu_free(virtualAddress = %p, size: %ld)\n", virtualAddress, size));
+
+	addr_t address = (addr_t)virtualAddress;
+	size = (size + B_PAGE_SIZE - 1) / B_PAGE_SIZE;
+		// get number of pages to map
+
+	// is the address within the valid range?
+	if (address < KERNEL_BASE
+		|| address + size >= KERNEL_BASE + kMaxKernelSize) {
+		panic("mmu_free: asked to unmap out of range region (%p, size %lx)\n",
+			(void *)address, size);
+	}
+
+	// unmap all pages within the range
+	for (uint32 i = 0; i < size; i++) {
+		unmap_page(address);
+		address += B_PAGE_SIZE;
+	}
+
+	if (address == sNextVirtualAddress) {
+		// we can actually reuse the virtual address space
+		sNextVirtualAddress -= size;
+	}
+}
+#endif
+
+
+/*!	Sets up the final and kernel accessible GDT and IDT tables.
+	BIOS calls won't work any longer after this function has
+	been called.
+*/
+extern "C" void
+mmu_init_for_kernel(void)
+{
+	TRACE(("mmu_init_for_kernel\n"));
+
+#ifdef __ARM__
+	// save the memory we've physically allocated
+	gKernelArgs.physical_allocated_range[0].size
+		= sNextPhysicalAddress - gKernelArgs.physical_allocated_range[0].start;
+
+	// Save the memory we've virtually allocated (for the kernel and other
+	// stuff)
+	gKernelArgs.virtual_allocated_range[0].start = KERNEL_BASE;
+	gKernelArgs.virtual_allocated_range[0].size
+		= sNextVirtualAddress - KERNEL_BASE;
+	gKernelArgs.num_virtual_allocated_ranges = 1;
+
+#ifdef TRACE_MEMORY_MAP
+	{
+		uint32 i;
+
+		dprintf("phys memory ranges:\n");
+		for (i = 0; i < gKernelArgs.num_physical_memory_ranges; i++) {
+			dprintf("    base 0x%08lx, length 0x%08lx\n",
+				gKernelArgs.physical_memory_range[i].start,
+				gKernelArgs.physical_memory_range[i].size);
+		}
+
+		dprintf("allocated phys memory ranges:\n");
+		for (i = 0; i < gKernelArgs.num_physical_allocated_ranges; i++) {
+			dprintf("    base 0x%08lx, length 0x%08lx\n",
+				gKernelArgs.physical_allocated_range[i].start,
+				gKernelArgs.physical_allocated_range[i].size);
+		}
+
+		dprintf("allocated virt memory ranges:\n");
+		for (i = 0; i < gKernelArgs.num_virtual_allocated_ranges; i++) {
+			dprintf("    base 0x%08lx, length 0x%08lx\n",
+				gKernelArgs.virtual_allocated_range[i].start,
+				gKernelArgs.virtual_allocated_range[i].size);
+		}
+	}
+#endif
+#endif
+}
+
+
+extern "C" void
+mmu_init(void)
+{
+	TRACE(("mmu_init\n"));
+
+#ifdef __ARM__
+	mmu_write_C1(mmu_read_C1() & ~((1<<29)|(1<<28)|(1<<0)));
+		// access flag disabled, TEX remap disabled, mmu disabled
+
+	uint32 highestRAMAddress = SDRAM_BASE;
+
+	// calculate lowest RAM adress from MEMORYMAP
+	for (uint32 i = 0; i < ARRAY_SIZE(LOADER_MEMORYMAP); i++) {
+		if (strcmp("RAM_free", LOADER_MEMORYMAP[i].name) == 0)
+			sNextPhysicalAddress = LOADER_MEMORYMAP[i].start;
+
+		if (strcmp("RAM_pt", LOADER_MEMORYMAP[i].name) == 0) {
+			sNextPageTableAddress = LOADER_MEMORYMAP[i].start
+				+ MMU_L1_TABLE_SIZE;
+			kPageTableRegionEnd = LOADER_MEMORYMAP[i].end;
+			sPageDirectory = (uint32 *) LOADER_MEMORYMAP[i].start;
+		}
+
+		if (strncmp("RAM_", LOADER_MEMORYMAP[i].name, 4) == 0) {
+			if (LOADER_MEMORYMAP[i].end > highestRAMAddress)
+				highestRAMAddress = LOADER_MEMORYMAP[i].end;
+		}
+	}
+
+	gKernelArgs.physical_memory_range[0].start = SDRAM_BASE;
+	gKernelArgs.physical_memory_range[0].size = highestRAMAddress - SDRAM_BASE;
+	gKernelArgs.num_physical_memory_ranges = 1;
+
+	gKernelArgs.physical_allocated_range[0].start = SDRAM_BASE;
+	gKernelArgs.physical_allocated_range[0].size = 0;
+	gKernelArgs.num_physical_allocated_ranges = 1;
+		// remember the start of the allocated physical pages
+
+	init_page_directory();
+
+	// map the page directory on the next vpage
+	gKernelArgs.arch_args.vir_pgdir = mmu_map_physical_memory(
+		(addr_t)sPageDirectory, MMU_L1_TABLE_SIZE, kDefaultPageFlags);
+
+	// map in a kernel stack
+	gKernelArgs.cpu_kstack[0].start = (addr_t)mmu_allocate(NULL,
+		KERNEL_STACK_SIZE + KERNEL_STACK_GUARD_PAGES * B_PAGE_SIZE);
+	gKernelArgs.cpu_kstack[0].size = KERNEL_STACK_SIZE
+		+ KERNEL_STACK_GUARD_PAGES * B_PAGE_SIZE;
+
+	TRACE(("kernel stack at 0x%lx to 0x%lx\n", gKernelArgs.cpu_kstack[0].start,
+		gKernelArgs.cpu_kstack[0].start + gKernelArgs.cpu_kstack[0].size));
+#endif
+}
+
+
+//	#pragma mark -
+
+
+extern "C" status_t
+platform_allocate_region(void **_address, size_t size, uint8 protection,
+	bool /*exactAddress*/)
+{
+#ifdef __ARM__
+	void *address = mmu_allocate(*_address, size);
+	if (address == NULL)
+		return B_NO_MEMORY;
+
+	*_address = address;
+	return B_OK;
+#else
+	return B_ERROR;
+#endif
+}
+
+
+extern "C" status_t
+platform_free_region(void *address, size_t size)
+{
+#ifdef __ARM__
+	mmu_free(address, size);
+#endif
+	return B_OK;
+}
+
+
+void
+platform_release_heap(struct stage2_args *args, void *base)
+{
+	// It will be freed automatically, since it is in the
+	// identity mapped region, and not stored in the kernel's
+	// page tables.
+}
+
+
+status_t
+platform_init_heap(struct stage2_args *args, void **_base, void **_top)
+{
+#ifdef __ARM__
+	void *heap = (void *)get_next_physical_address(args->heap_size);
+	if (heap == NULL)
+		return B_NO_MEMORY;
+
+	*_base = heap;
+	*_top = (void *)((int8 *)heap + args->heap_size);
+	return B_OK;
+#else
+	return B_ERROR;
+#endif
+}