init.c

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	/*
	 * Make sure that the initrd is within a valid area of
	 * memory.
	 */
	if (initrd_start) {
		unsigned long phys_initrd_start, phys_initrd_end;
		unsigned int i;

		phys_initrd_start = __pa(initrd_start);
		phys_initrd_end   = __pa(initrd_end);

		for (i = 0; i < mi->nr_banks; i++) {
			unsigned long bank_end;

			bank_end = mi->bank[i].start + mi->bank[i].size;

			if (mi->bank[i].start <= phys_initrd_start &&
			    phys_initrd_end <= bank_end)
				initrd_node = mi->bank[i].node;
		}
	}

	if (initrd_node == -1) {
		printk(KERN_ERR "initrd (0x%08lx - 0x%08lx) extends beyond "
		       "physical memory - disabling initrd\n",
		       initrd_start, initrd_end);
		initrd_start = initrd_end = 0;
	}
#endif

	return initrd_node;
}

/*
 * Reserve the various regions of node 0
 */
static __init void reserve_node_zero(unsigned int bootmap_pfn, unsigned int bootmap_pages)
{
	pg_data_t *pgdat = NODE_DATA(0);

	/*
	 * Register the kernel text and data with bootmem.
	 * Note that this can only be in node 0.
	 */
	reserve_bootmem_node(pgdat, __pa(&_stext), &_end - &_stext);

#ifdef CONFIG_CPU_32
	/*
	 * Reserve the page tables.  These are already in use,
	 * and can only be in node 0.
	 */
	reserve_bootmem_node(pgdat, __pa(swapper_pg_dir),
			     PTRS_PER_PGD * sizeof(void *));
#endif
	/*
	 * And don't forget to reserve the allocator bitmap,
	 * which will be freed later.
	 */
	reserve_bootmem_node(pgdat, bootmap_pfn << PAGE_SHIFT,
			     bootmap_pages << PAGE_SHIFT);

	/*
	 * Hmm... This should go elsewhere, but we really really
	 * need to stop things allocating the low memory; we need
	 * a better implementation of GFP_DMA which does not assume
	 * that DMA-able memory starts at zero.
	 */
	if (machine_is_integrator())
		reserve_bootmem_node(pgdat, 0, __pa(swapper_pg_dir));
	/*
	 * These should likewise go elsewhere.  They pre-reserve
	 * the screen memory region at the start of main system
	 * memory.
	 */
	if (machine_is_archimedes() || machine_is_a5k())
		reserve_bootmem_node(pgdat, 0x02000000, 0x00080000);
	if (machine_is_p720t())
		reserve_bootmem_node(pgdat, 0xc0000000, 0x00014000);
}

/*
 * Register all available RAM in this node with the bootmem allocator.
 */
static inline void free_bootmem_node_bank(int node, struct meminfo *mi)
{
	pg_data_t *pgdat = NODE_DATA(node);
	int bank;

	for (bank = 0; bank < mi->nr_banks; bank++)
		if (mi->bank[bank].node == node)
			free_bootmem_node(pgdat, mi->bank[bank].start,
					  mi->bank[bank].size);
}

/*
 * Initialise the bootmem allocator for all nodes.  This is called
 * early during the architecture specific initialisation.
 */
void __init bootmem_init(struct meminfo *mi)
{
	struct node_info node_info[NR_NODES], *np = node_info;
	unsigned int bootmap_pages, bootmap_pfn, map_pg;
	int node, initrd_node;

	bootmap_pages = find_memend_and_nodes(mi, np);
	bootmap_pfn   = find_bootmap_pfn(0, mi, bootmap_pages);
	initrd_node   = check_initrd(mi);

	map_pg = bootmap_pfn;
	
	for (node = 0; node < numnodes; node++, np++) {
		/*
		 * If there are no pages in this node, ignore it.
		 * Note that node 0 must always have some pages.
		 */
		if (np->end == 0) {
			if (node == 0)
				BUG();
			continue;
		}

		/*
		 * Initialise the bootmem allocator.
		 */
		init_bootmem_node(NODE_DATA(node), map_pg, np->start, np->end);
		free_bootmem_node_bank(node, mi);
		map_pg += np->bootmap_pages;

		/*
		 * If this is node 0, we need to reserve some areas ASAP -
		 * we may use bootmem on node 0 to setup the other nodes.
		 */
		if (node == 0)
			reserve_node_zero(bootmap_pfn, bootmap_pages);
	}


#ifdef CONFIG_BLK_DEV_INITRD
	if (initrd_node >= 0)
		reserve_bootmem_node(NODE_DATA(initrd_node), __pa(initrd_start),
				     initrd_end - initrd_start);
#endif

	if (map_pg != bootmap_pfn + bootmap_pages)
		BUG();
}

/*
 * paging_init() sets up the page tables, initialises the zone memory
 * maps, and sets up the zero page, bad page and bad page tables.
 */
void __init paging_init(struct meminfo *mi, struct machine_desc *mdesc)
{
	void *zero_page, *bad_page, *bad_table;
	int node;

	memcpy(&meminfo, mi, sizeof(meminfo));

	/*
	 * allocate what we need for the bad pages.
	 * note that we count on this going ok.
	 */
	zero_page = alloc_bootmem_low_pages(PAGE_SIZE);
	bad_page  = alloc_bootmem_low_pages(PAGE_SIZE);
	bad_table = alloc_bootmem_low_pages(TABLE_SIZE);

	/*
	 * initialise the page tables.
	 */
	memtable_init(mi);
	if (mdesc->map_io)
		mdesc->map_io();
	flush_tlb_all();

	/*
	 * initialise the zones within each node
	 */
	for (node = 0; node < numnodes; node++) {
		unsigned long zone_size[MAX_NR_ZONES];
		unsigned long zhole_size[MAX_NR_ZONES];
		struct bootmem_data *bdata;
		pg_data_t *pgdat;
		int i;

		/*
		 * Initialise the zone size information.
		 */
		for (i = 0; i < MAX_NR_ZONES; i++) {
			zone_size[i]  = 0;
			zhole_size[i] = 0;
		}

		pgdat = NODE_DATA(node);
		bdata = pgdat->bdata;

		/*
		 * The size of this node has already been determined.
		 * If we need to do anything fancy with the allocation
		 * of this memory to the zones, now is the time to do
		 * it.
		 */
		zone_size[0] = bdata->node_low_pfn -
				(bdata->node_boot_start >> PAGE_SHIFT);

		/*
		 * For each bank in this node, calculate the size of the
		 * holes.  holes = node_size - sum(bank_sizes_in_node)
		 */
		zhole_size[0] = zone_size[0];
		for (i = 0; i < mi->nr_banks; i++) {
			if (mi->bank[i].node != node)
				continue;

			zhole_size[0] -= mi->bank[i].size >> PAGE_SHIFT;
		}

		free_area_init_node(node, pgdat, 0, zone_size,
				bdata->node_boot_start, zhole_size);
	}

	/*
	 * finish off the bad pages once
	 * the mem_map is initialised
	 */
	memzero(zero_page, PAGE_SIZE);
	memzero(bad_page, PAGE_SIZE);

	empty_zero_page = virt_to_page(zero_page);
	empty_bad_page  = virt_to_page(bad_page);
	empty_bad_pte_table = ((pte_t *)bad_table) + TABLE_OFFSET;
}

/*
 * mem_init() marks the free areas in the mem_map and tells us how much
 * memory is free.  This is done after various parts of the system have
 * claimed their memory after the kernel image.
 */
void __init mem_init(void)
{
	unsigned int codepages, datapages, initpages;
	int i, node;

	codepages = &_etext - &_text;
	datapages = &_end - &_etext;
	initpages = &__init_end - &__init_begin;

	high_memory = (void *)__va(meminfo.end);
	max_mapnr   = virt_to_page(high_memory) - mem_map;

	/*
	 * We may have non-contiguous memory.
	 */
	if (meminfo.nr_banks != 1)
		create_memmap_holes(&meminfo);

	/* this will put all unused low memory onto the freelists */
	for (node = 0; node < numnodes; node++)
		totalram_pages += free_all_bootmem_node(NODE_DATA(node));

	/*
	 * Since our memory may not be contiguous, calculate the
	 * real number of pages we have in this system
	 */
	printk(KERN_INFO "Memory:");

	num_physpages = 0;
	for (i = 0; i < meminfo.nr_banks; i++) {
		num_physpages += meminfo.bank[i].size >> PAGE_SHIFT;
		printk(" %ldMB", meminfo.bank[i].size >> 20);
	}

	printk(" = %luMB total\n", num_physpages >> (20 - PAGE_SHIFT));
	printk(KERN_NOTICE "Memory: %luKB available (%dK code, "
		"%dK data, %dK init)\n",
		(unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
		codepages >> 10, datapages >> 10, initpages >> 10);

	if (PAGE_SIZE >= 16384 && num_physpages <= 128) {
		extern int sysctl_overcommit_memory;
		/*
		 * On a machine this small we won't get
		 * anywhere without overcommit, so turn
		 * it on by default.
		 */
		sysctl_overcommit_memory = 1;
	}
}

static inline void free_area(unsigned long addr, unsigned long end, char *s)
{
	unsigned int size = (end - addr) >> 10;

	for (; addr < end; addr += PAGE_SIZE) {
		struct page *page = virt_to_page(addr);
		ClearPageReserved(page);
		set_page_count(page, 1);
		free_page(addr);
		totalram_pages++;
	}

	if (size)
		printk("Freeing %s memory: %dK\n", s, size);
}

void free_initmem(void)
{
	if (!machine_is_integrator()) {
		free_area((unsigned long)(&__init_begin),
			  (unsigned long)(&__init_end),
			  "init");
	}
}

#ifdef CONFIG_BLK_DEV_INITRD

static int keep_initrd;

void free_initrd_mem(unsigned long start, unsigned long end)
{
	if (!keep_initrd)
		free_area(start, end, "initrd");
}

static int __init keepinitrd_setup(char *__unused)
{
	keep_initrd = 1;
	return 1;
}

__setup("keepinitrd", keepinitrd_setup);
#endif

void si_meminfo(struct sysinfo *val)
{
	val->totalram  = totalram_pages;
	val->sharedram = 0;
	val->freeram   = nr_free_pages();
	val->bufferram = atomic_read(&buffermem_pages);
	val->totalhigh = 0;
	val->freehigh  = 0;
	val->mem_unit  = PAGE_SIZE;
}