[ARM PATCH] 2154/2: XIP kernel for ARM

Patch from Nicolas Pitre

This patch allows for the kernel to be configured for XIP.
A lot of people are using semi hacked up XIP patches already so
it is a good idea to have a generic and clean implementation 
supporting all ARM targets. The patch isn't too intrusive.

It involves:

- modifying the kernel entry code to map separate .text and .data
  sections in the initial page table, as well as relocating
  .data to ram when needed

- modifying the linker script to account for the different VMA and
  LMA for .data, as well as making sure that .init.data gets
  relocated to ram

- adding the final kernel mapping with a new MT_ROM mem type

- distinguishing between XIP and non-XIP for bootmem and memory
  resource declaration

- and adding proper target handling to Makefiles.

While at it, this also cleans up the kernel boot code a bit
so the kernel can now be compiled for any address in ram,
removing the need for a relation between kernel address and
start of ram.  Also throws in some more comments.

And finally the _text, _etext, _end and similar variables are now
declared extern void instead of extern char, or even extern int.
That allows for operations on their address directly without any
cast, and trying to reference them by mistake would yield an 
error which is a good thing.

Tested both configurations: XIP and non XIP, the later 
producing a kernel for execution from ram just as before.

Signed-off-by: Nicolas Pitre 
Signed-off-by: Russell King

arch/arm/Kconfig

@@ -343,6 +343,50 @@ config ZBOOT_ROM_BSS
 	  while the decompressor is running.  Unless you have special requirements,
 	  you should not change this value.
 
+config XIP_KERNEL
+	bool "Kernel Execute-In-Place from ROM"
+	depends on !ZBOOT_ROM
+	help
+	  Execute-In-Place allows the kernel to run from non-volatile storage
+	  directly addressable by the CPU, such as NOR flash. This saves RAM
+	  space since the text section of the kernel is not loaded from flash
+	  to RAM.  Read-write sections, such as the data section and stack,
+	  are still copied to RAM.  The XIP kernel is not compressed since
+	  it has to run directly from flash, so it will take more space to
+	  store it.  The flash address used to link the kernel object files,
+	  and for storing it, is configuration dependent. Therefore, if you
+	  say Y here, you must know the proper physical address where to
+	  store the kernel image depending on your own flash memory usage.
+
+	  Also note that the make target becomes "make xipImage" rather than
+	  "make zImage" or "make Image".  The final kernel binary to put in
+	  ROM memory will be arch/arm/boot/xipImage.
+
+	  If unsure, say N.
+
+config XIP_PHYS_ADDR
+	hex "XIP Kernel Physical Location"
+	depends on XIP_KERNEL
+	default "0x00080000"
+	help
+	  This is the physical address in your flash memory the kernel will
+	  be linked for and stored to.  This address is dependent on your
+	  own flash usage.
+
+	  Please note that, if you're using MTD, you must use a flash chip
+	  that is NOT handled by MTD or the flash will be turned into non
+	  data mode for status and query purposes which will instantaneously
+	  crash the kernel.
+
+	  MTD can however be used with a XIP kernel on the same flash chip
+	  but only if the flash memory supports multiple partitions in
+	  hardware, like with the Intel K3 flash parts, and only if the
+	  kernel is not stored within the firrst hardware partition of the
+	  chip.
+
+	  In any case, make sure that MTD support is configured out for
+	  the first attempt.
+
 if (ARCH_SA1100 || ARCH_INTEGRATOR)
 
 config CPU_FREQ

arch/arm/Makefile

@@ -65,8 +65,6 @@ AFLAGS		+=$(CFLAGS_ABI) $(arch-y) $(tune-y) -msoft-float
 CHECKFLAGS	+= -D__arm__
 
 #Default value
-DATAADDR	:= .
-
 head-y		:= arch/arm/kernel/head.o arch/arm/kernel/init_task.o
 textaddr-y	:= 0xC0008000
 
@@ -110,6 +108,15 @@ export CFLAGS_3c589_cs.o
 endif
 
 TEXTADDR := $(textaddr-y)
+ifeq ($(CONFIG_XIP_KERNEL),y)
+  DATAADDR := $(TEXTADDR)
+  # Replace phys addr with virt addr while keeping offset from base.
+  xipaddr-y ?= 0xe8000000
+  TEXTADDR := $(shell echo $(CONFIG_XIP_PHYS_ADDR) $(xipaddr-y) | \
+                      awk --non-decimal-data '/[:xdigit:]/ \
+                          { printf("0x%x\n", and($$1, 0x000fffff) + $$2) }' )
+endif
+
 ifeq ($(incdir-y),)
 incdir-y := $(machine-y)
 endif
@@ -120,7 +127,7 @@ else
 MACHINE  :=
 endif
   
-export	TEXTADDR GZFLAGS
+export	TEXTADDR DATAADDR GZFLAGS
 
 # Do we have FASTFPE?
 FASTFPE		:=arch/arm/fastfpe
@@ -142,7 +149,11 @@ drivers-$(CONFIG_ARCH_L7200)	+= drivers/acorn/char/
 libs-y				+= arch/arm/lib/
 
 # Default target when executing plain make
+ifeq ($(CONFIG_XIP_KERNEL),y)
+all: xipImage
+else
 all: zImage
+endif
 
 boot := arch/arm/boot
 
@@ -169,7 +180,7 @@ maketools: include/asm-arm/constants.h include/linux/version.h FORCE
 # Convert bzImage to zImage
 bzImage: zImage
 
-zImage Image bootpImage uImage: vmlinux
+zImage Image xipImage bootpImage uImage: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@
 
 zinstall install: vmlinux
@@ -195,6 +206,7 @@ include/asm-$(ARCH)/constants.h: arch/$(ARCH)/kernel/asm-offsets.s
 define archhelp
   echo  '* zImage        - Compressed kernel image (arch/$(ARCH)/boot/zImage)'
   echo  '  Image         - Uncompressed kernel image (arch/$(ARCH)/boot/Image)'
+  echo  '* xipImage      - XIP kernel image, if configured (arch/$(ARCH)/boot/xipImage)'
   echo  '  bootpImage    - Combined zImage and initial RAM disk' 
   echo  '                  (supply initrd image via make variable INITRD=<path>)'
   echo  '  install       - Install uncompressed kernel'

arch/arm/boot/Makefile

@@ -24,7 +24,24 @@ INITRD_PHYS := $(initrd_phys-y)
 
 export ZRELADDR INITRD_PHYS PARAMS_PHYS
 
-targets := Image zImage bootpImage uImage
+targets := Image zImage xipImage bootpImage uImage
+
+ifeq ($(CONFIG_XIP_KERNEL),y)
+
+$(obj)/xipImage: vmlinux FORCE
+	$(call if_changed,objcopy)
+	@echo '  Kernel: $@ is ready (physical address: $(CONFIG_XIP_PHYS_ADDR))'
+
+$(obj)/Image $(obj)/zImage: FORCE
+	@echo 'Kernel configured for XIP (CONFIG_XIP_KERNEL=y)'
+	@echo 'Only the xipImage target is available in this case'
+	@false
+
+else
+
+$(obj)/xipImage: FORCE
+	@echo 'Kernel not configured for XIP (CONFIG_XIP_KERNEL!=y)'
+	@false
 
 $(obj)/Image: vmlinux FORCE
 	$(call if_changed,objcopy)
@@ -37,6 +54,8 @@ $(obj)/zImage:	$(obj)/compressed/vmlinux FORCE
 	$(call if_changed,objcopy)
 	@echo '  Kernel: $@ is ready'
 
+endif
+
 quiet_cmd_uimage = UIMAGE  $@
       cmd_uimage = $(CONFIG_SHELL) $(MKIMAGE) -A arm -O linux -T kernel \
 		   -C none -a $(ZRELADDR) -e $(ZRELADDR) \

arch/arm/kernel/Makefile

@@ -2,7 +2,7 @@
 # Makefile for the linux kernel.
 #
 
-AFLAGS_head.o := -DTEXTADDR=$(TEXTADDR)
+AFLAGS_head.o := -DTEXTADDR=$(TEXTADDR) -DDATAADDR=$(DATAADDR)
 
 # Object file lists.
 

arch/arm/kernel/asm-offsets.c

@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <asm/mach/arch.h>
 #include <asm/thread_info.h>
+#include <asm/memory.h>
 
 /*
  * Make sure that the compiler and target are compatible.
@@ -72,6 +73,7 @@ int main(void)
   DEFINE(VM_EXEC,	       	VM_EXEC);
   BLANK();
   DEFINE(PAGE_SZ,	       	PAGE_SIZE);
+  DEFINE(VIRT_OFFSET,	       	PAGE_OFFSET);
   BLANK();
   DEFINE(SYS_ERROR0,		0x9f0000);
   BLANK();

arch/arm/kernel/head.S

@@ -19,17 +19,16 @@
 #include <asm/ptrace.h>
 #include <asm/constants.h>
 
+#ifndef CONFIG_XIP_KERNEL
 /*
  * We place the page tables 16K below TEXTADDR.  Therefore, we must make sure
  * that TEXTADDR is correctly set.  Currently, we expect the least significant
  * 16 bits to be 0x8000, but we could probably relax this restriction to
- * TEXTADDR > PAGE_OFFSET + 0x4000
+ * TEXTADDR >= PAGE_OFFSET + 0x4000
  *
  * Note that swapper_pg_dir is the virtual address of the page tables, and
  * pgtbl gives us a position-independent reference to these tables.  We can
  * do this because stext == TEXTADDR
- *
- * swapper_pg_dir, pgtbl and krnladr are all closely related.
  */
 #if (TEXTADDR & 0xffff) != 0x8000
 #error TEXTADDR must start at 0xXXXX8000
@@ -38,19 +37,35 @@
 	.globl	swapper_pg_dir
 	.equ	swapper_pg_dir, TEXTADDR - 0x4000
 
-	.macro	pgtbl, reg
-	adr	\reg, stext
-	sub	\reg, \reg, #0x4000
+	.macro	pgtbl, rd, phys
+	adr	\rd, stext
+	sub	\rd, \rd, #0x4000
 	.endm
-
+#else
 /*
- * Since the page table is closely related to the kernel start address, we
- * can convert the page table base address to the base address of the section
- * containing both.
+ * XIP Kernel:
+ *
+ * We place the page tables 16K below DATAADDR.  Therefore, we must make sure
+ * that DATAADDR is correctly set.  Currently, we expect the least significant
+ * 16 bits to be 0x8000, but we could probably relax this restriction to
+ * DATAADDR >= PAGE_OFFSET + 0x4000
+ *
+ * Note that pgtbl is meant to return the physical address of swapper_pg_dir.
+ * We can't make it relative to the kernel position in this case since
+ * the kernel can physically be anywhere.
  */
-	.macro	krnladr, rd, pgtable
-	bic	\rd, \pgtable, #0x000ff000
+#if (DATAADDR & 0xffff) != 0x8000
+#error DATAADDR must start at 0xXXXX8000
+#endif
+
+	.globl	swapper_pg_dir
+	.equ	swapper_pg_dir, DATAADDR - 0x4000
+
+	.macro	pgtbl, rd, phys
+	ldr	\rd, =((DATAADDR - 0x4000) - VIRT_OFFSET)
+	add	\rd, \rd, \phys
 	.endm
+#endif
 
 /*
  * Kernel startup entry point.
@@ -99,6 +114,8 @@ ENTRY(stext)
 	.type	__switch_data, %object
 __switch_data:
 	.long	__mmap_switched
+	.long	__data_loc			@ r2
+	.long	__data_start			@ r3
 	.long	__bss_start			@ r4
 	.long	_end				@ r5
 	.long	processor_id			@ r6
@@ -136,12 +153,20 @@ __turn_mmu_on:
  */
 	.align	5
 __mmap_switched:
-	adr	r3, __switch_data + 4
-	ldmia	r3, {r4, r5, r6, r7, r8, sp}
+	adr	r2, __switch_data + 4
+	ldmia	r2, {r2, r3, r4, r5, r6, r7, r8, sp}
+
+	cmp	r2, r3				@ Copy data segment if needed
+1:	cmpne	r3, r4
+	ldrne	fp, [r2], #4
+	strne	fp, [r3], #4
+	bne	1b
+
 	mov	fp, #0				@ Clear BSS (and zero fp)
 1:	cmp	r4, r5
 	strcc	fp, [r4],#4
 	bcc	1b
+
 	str	r9, [r6]			@ Save processor ID
 	str	r1, [r7]			@ Save machine type
 	bic	r2, r0, #2			@ Clear 'A' bit
@@ -156,16 +181,13 @@ __mmap_switched:
  * amount which are required to get the kernel running, which
  * generally means mapping in the kernel code.
  *
- * We only map in 4MB of RAM, which should be sufficient in
- * all cases.
- *
  * r5 = physical address of start of RAM
  * r6 = physical IO address
  * r7 = byte offset into page tables for IO
  * r8 = page table flags
  */
 __create_page_tables:
-	pgtbl	r4				@ page table address
+	pgtbl	r4, r5				@ page table address
 
 	/*
 	 * Clear the 16K level 1 swapper page table
@@ -183,28 +205,50 @@ __create_page_tables:
 	/*
 	 * Create identity mapping for first MB of kernel to
 	 * cater for the MMU enable.  This identity mapping
-	 * will be removed by paging_init()
+	 * will be removed by paging_init().  We use our current program
+	 * counter to determine corresponding section base address.
 	 */
-	krnladr	r2, r4				@ start of kernel
-	add	r3, r8, r2			@ flags + kernel base
-	str	r3, [r4, r2, lsr #18]		@ identity mapping
+	mov	r2, pc, lsr #20			@ start of kernel section
+	add	r3, r8, r2, lsl #20		@ flags + kernel base
+	str	r3, [r4, r2, lsl #2]		@ identity mapping
 
 	/*
 	 * Now setup the pagetables for our kernel direct
 	 * mapped region.  We round TEXTADDR down to the
-	 * nearest megabyte boundary.
+	 * nearest megabyte boundary.  It is assumed that
+	 * the kernel fits within 4 contigous 1MB sections.
 	 */
-	add	r0, r4, #(TEXTADDR & 0xff000000) >> 18 @ start of kernel
-	bic	r2, r3, #0x00f00000
-	str	r2, [r0]			@ PAGE_OFFSET + 0MB
-	add	r0, r0, #(TEXTADDR & 0x00f00000) >> 18
-	str	r3, [r0], #4			@ KERNEL + 0MB
+	add	r0, r4,  #(TEXTADDR & 0xff000000) >> 18	@ start of kernel
+	str	r3, [r0, #(TEXTADDR & 0x00f00000) >> 18]!
 	add	r3, r3, #1 << 20
-	str	r3, [r0], #4			@ KERNEL + 1MB
+	str	r3, [r0, #4]!			@ KERNEL + 1MB
 	add	r3, r3, #1 << 20
-	str	r3, [r0], #4			@ KERNEL + 2MB
+	str	r3, [r0, #4]!			@ KERNEL + 2MB
 	add	r3, r3, #1 << 20
-	str	r3, [r0], #4			@ KERNEL + 3MB
+	str	r3, [r0, #4]			@ KERNEL + 3MB
+
+	/*
+	 * Then map first 1MB of ram in case it contains our boot params.
+	 */
+	add	r0, r4, #VIRT_OFFSET >> 18
+	add	r2, r5, r8
+	str	r2, [r0]
+
+#ifdef CONFIG_XIP_KERNEL
+	/*
+	 * Map some ram to cover our .data and .bss areas.
+	 * Mapping 3MB should be plenty.
+	 */
+	sub	r3, r4, r5
+	mov	r3, r3, lsr #20
+	add	r0, r0, r3, lsl #2
+	add	r2, r2, r3, lsl #20
+	str	r2, [r0], #4
+	add	r2, r2, #(1 << 20)
+	str	r2, [r0], #4
+	add	r2, r2, #(1 << 20)
+	str	r2, [r0]
+#endif
 
 	bic	r8, r8, #0x0c			@ turn off cacheable
 						@ and bufferable bits
@@ -255,6 +299,7 @@ __create_page_tables:
 	str	r3, [r0]
 #endif
 	mov	pc, lr
+	.ltorg
 
 
 

arch/arm/kernel/setup.c

@@ -59,7 +59,7 @@ extern void convert_to_tag_list(struct tag *tags);
 extern void squash_mem_tags(struct tag *tag);
 extern void reboot_setup(char *str);
 extern int root_mountflags;
-extern int _stext, _text, _etext, _edata, _end;
+extern void _stext, _text, _etext, __data_start, _edata, _end;
 
 unsigned int processor_id;
 unsigned int __machine_arch_type;
@@ -113,7 +113,7 @@ static union { char c[4]; unsigned long l; } endian_test __initdata = { { 'l', '
  */
 static struct resource mem_res[] = {
 	{ "Video RAM",   0,     0,     IORESOURCE_MEM			},
-	{ "Kernel code", 0,     0,     IORESOURCE_MEM			},
+	{ "Kernel text", 0,     0,     IORESOURCE_MEM			},
 	{ "Kernel data", 0,     0,     IORESOURCE_MEM			}
 };
 
@@ -447,10 +447,10 @@ request_standard_resources(struct meminfo *mi, struct machine_desc *mdesc)
 	struct resource *res;
 	int i;
 
-	kernel_code.start  = __virt_to_phys(init_mm.start_code);
-	kernel_code.end    = __virt_to_phys(init_mm.end_code - 1);
-	kernel_data.start  = __virt_to_phys(init_mm.end_code);
-	kernel_data.end    = __virt_to_phys(init_mm.brk - 1);
+	kernel_code.start   = virt_to_phys(&_text);
+	kernel_code.end     = virt_to_phys(&_etext - 1);
+	kernel_data.start   = virt_to_phys(&__data_start);
+	kernel_data.end     = virt_to_phys(&_end - 1);
 
 	for (i = 0; i < mi->nr_banks; i++) {
 		unsigned long virt_start, virt_end;

arch/arm/kernel/vmlinux.lds.S

@@ -4,6 +4,7 @@
  */
 
 #include <asm-generic/vmlinux.lds.h>
+#include <linux/config.h>
 	
 OUTPUT_ARCH(arm)
 ENTRY(stext)
@@ -17,7 +18,6 @@ SECTIONS
 	. = TEXTADDR;
 	.init : {			/* Init code and data		*/
 		_stext = .;
-		__init_begin = .;
 			_sinittext = .;
 			*(.init.text)
 			_einittext = .;
@@ -30,7 +30,6 @@ SECTIONS
 		__tagtable_begin = .;
 			*(.taglist)
 		__tagtable_end = .;
-			*(.init.data)
 		. = ALIGN(16);
 		__setup_start = .;
 			*(.init.setup)
@@ -57,8 +56,12 @@ SECTIONS
 		__initramfs_start = .;
 			usr/built-in.o(.init.ramfs)
 		__initramfs_end = .;
+#ifndef CONFIG_XIP_KERNEL
+		__init_begin = _stext;
+		*(.init.data)
 		. = ALIGN(4096);
 		__init_end = .;
+#endif
 	}
 
 	/DISCARD/ : {			/* Exit code and data		*/
@@ -79,8 +82,6 @@ SECTIONS
 			*(.glue_7)
 			*(.glue_7t)
 		*(.got)			/* Global offset table		*/
-
-		_etext = .;		/* End of text section		*/
 	}
 
 	. = ALIGN(16);
@@ -92,15 +93,33 @@ SECTIONS
 
 	RODATA
 
+	_etext = .;			/* End of text and rodata section */
+
+#ifdef CONFIG_XIP_KERNEL
+	__data_loc = ALIGN(4);		/* location in binary */
+	. = DATAADDR;
+#else
 	. = ALIGN(8192);
+	__data_loc = .;
+#endif
+
+	.data : AT(__data_loc) {
+		__data_start = .;	/* address in memory */
 
-	.data : {
 		/*
 		 * first, the init task union, aligned
 		 * to an 8192 byte boundary.
 		 */
 		*(.init.task)
 
+#ifdef CONFIG_XIP_KERNEL
+		. = ALIGN(4096);
+		__init_begin = .;
+		*(.init.data)
+		. = ALIGN(4096);
+		__init_end = .;
+#endif
+
 		. = ALIGN(4096);
 		__nosave_begin = .;
 		*(.data.nosave)
@@ -126,7 +145,7 @@ SECTIONS
 		__bss_start = .;	/* BSS				*/
 		*(.bss)
 		*(COMMON)
-		_end = . ;
+		_end = .;
 	}
 					/* Stabs debugging sections.	*/
 	.stab 0 : { *(.stab) }

arch/arm/mm/init.c

@@ -30,7 +30,7 @@
 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 
 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
-extern char _stext, _text, _etext, _end, __init_begin, __init_end;
+extern void _stext, _text, _etext, __data_start, _end, __init_begin, __init_end;
 extern unsigned long phys_initrd_start;
 extern unsigned long phys_initrd_size;
 
@@ -282,7 +282,11 @@ static __init void reserve_node_zero(unsigned int bootmap_pfn, unsigned int boot
 	 * Register the kernel text and data with bootmem.
 	 * Note that this can only be in node 0.
 	 */
+#ifdef CONFIG_XIP_KERNEL
+	reserve_bootmem_node(pgdat, __pa(&__data_start), &_end - &__data_start);
+#else
 	reserve_bootmem_node(pgdat, __pa(&_stext), &_end - &_stext);
+#endif
 
 	/*
 	 * Reserve the page tables.  These are already in use,
@@ -540,7 +544,7 @@ void __init mem_init(void)
 	int i, node;
 
 	codepages = &_etext - &_text;
-	datapages = &_end - &_etext;
+	datapages = &_end - &__data_start;
 	initpages = &__init_end - &__init_begin;
 
 #ifndef CONFIG_DISCONTIGMEM

arch/arm/mm/mm-armv.c

@@ -326,6 +326,10 @@ static struct mem_types mem_types[] __initdata = {
 	[MT_MEMORY] = {
 		.prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE,
 		.domain    = DOMAIN_KERNEL,
+	},
+	[MT_ROM] = {
+		.prot_sect = PMD_TYPE_SECT,
+		.domain    = DOMAIN_KERNEL,
 	}
 };
 
@@ -359,6 +363,7 @@ static void __init build_mem_type_table(void)
 		mem_types[MT_MINICLEAN].prot_sect  |= PMD_BIT4;
 		mem_types[MT_VECTORS].prot_l1      |= PMD_BIT4;
 		mem_types[MT_MEMORY].prot_sect     |= PMD_BIT4;
+		mem_types[MT_ROM].prot_sect        |= PMD_BIT4;
 	}
 
 	/*
@@ -370,6 +375,7 @@ static void __init build_mem_type_table(void)
 		 * kernel memory mapping.
 		 */
 		mem_types[MT_MEMORY].prot_sect &= ~PMD_BIT4;
+		mem_types[MT_ROM].prot_sect &= ~PMD_BIT4;
 		/*
 		 * Mark cache clean areas read only from SVC mode
 		 * and no access from userspace.
@@ -389,6 +395,7 @@ static void __init build_mem_type_table(void)
 
 	mem_types[MT_VECTORS].prot_l1 |= ecc_mask;
 	mem_types[MT_MEMORY].prot_sect |= ecc_mask | cp->pmd;
+	mem_types[MT_ROM].prot_sect |= cp->pmd;
 
 	for (i = 0; i < 16; i++) {
 		unsigned long v = pgprot_val(protection_map[i]);
@@ -433,7 +440,7 @@ static void __init create_mapping(struct map_desc *md)
 		return;
 	}
 
-	if (md->type == MT_DEVICE &&
+	if ((md->type == MT_DEVICE || md->type == MT_ROM) &&
 	    md->virtual >= PAGE_OFFSET && md->virtual < VMALLOC_END) {
 		printk(KERN_WARNING "BUG: mapping for 0x%08lx at 0x%08lx "
 		       "overlaps vmalloc space\n",
@@ -508,6 +515,8 @@ void setup_mm_for_reboot(char mode)
 	}
 }
 
+extern void _stext, _etext;
+
 /*
  * Setup initial mappings.  We use the page we allocated for zero page to hold
  * the mappings, which will get overwritten by the vectors in traps_init().
@@ -534,6 +543,14 @@ void __init memtable_init(struct meminfo *mi)
 		p ++;
 	}
 
+#ifdef CONFIG_XIP_KERNEL
+	p->physical   = CONFIG_XIP_PHYS_ADDR & PMD_MASK;
+	p->virtual    = (unsigned long)&_stext & PMD_MASK;
+	p->length     = ((unsigned long)&_etext - p->virtual + ~PMD_MASK) & PMD_MASK;
+	p->type       = MT_ROM;
+	p ++;
+#endif
+
 #ifdef FLUSH_BASE
 	p->physical   = FLUSH_BASE_PHYS;
 	p->virtual    = FLUSH_BASE;

include/asm-arm/mach/map.h

@@ -23,6 +23,7 @@ struct meminfo;
 #define MT_MINICLEAN	2
 #define MT_VECTORS	3
 #define MT_MEMORY	4
+#define MT_ROM		5
 
 extern void create_memmap_holes(struct meminfo *);
 extern void memtable_init(struct meminfo *);