setup.c

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	new_nr = new_bios_entry;   /* retain count for new bios entries */

	/* copy new bios mapping into original location */
	memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
	*pnr_map = new_nr;

	return 0;
}

/*
 * Copy the BIOS e820 map into a safe place.
 *
 * Sanity-check it while we're at it..
 *
 * If we're lucky and live on a modern system, the setup code
 * will have given us a memory map that we can use to properly
 * set up memory.  If we aren't, we'll fake a memory map.
 *
 * We check to see that the memory map contains at least 2 elements
 * before we'll use it, because the detection code in setup.S may
 * not be perfect and most every PC known to man has two memory
 * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
 * thinkpad 560x, for example, does not cooperate with the memory
 * detection code.)
 */
static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
{
	/* Only one memory region (or negative)? Ignore it */
	if (nr_map < 2)
		return -1;

	do {
		unsigned long long start = biosmap->addr;
		unsigned long long size = biosmap->size;
		unsigned long long end = start + size;
		unsigned long type = biosmap->type;

		/* Overflow in 64 bits? Ignore the memory map. */
		if (start > end)
			return -1;

		/*
		 * Some BIOSes claim RAM in the 640k - 1M region.
		 * Not right. Fix it up.
		 */
		if (type == E820_RAM) {
			if (start < 0x100000ULL && end > 0xA0000ULL) {
				if (start < 0xA0000ULL)
					add_memory_region(start, 0xA0000ULL-start, type);
				if (end <= 0x100000ULL)
					continue;
				start = 0x100000ULL;
				size = end - start;
			}
		}
		add_memory_region(start, size, type);
	} while (biosmap++,--nr_map);
	return 0;
}

/*
 * Do NOT EVER look at the BIOS memory size location.
 * It does not work on many machines.
 */
#define LOWMEMSIZE()	(0x9f000)

static void __init setup_memory_region(void)
{
	char *who = "BIOS-e820";

	/*
	 * Try to copy the BIOS-supplied E820-map.
	 *
	 * Otherwise fake a memory map; one section from 0k->640k,
	 * the next section from 1mb->appropriate_mem_k
	 */
	sanitize_e820_map(E820_MAP, &E820_MAP_NR);
	if (copy_e820_map(E820_MAP, E820_MAP_NR) < 0) {
		unsigned long mem_size;

		/* compare results from other methods and take the greater */
		if (ALT_MEM_K < EXT_MEM_K) {
			mem_size = EXT_MEM_K;
			who = "BIOS-88";
		} else {
			mem_size = ALT_MEM_K;
			who = "BIOS-e801";
		}

		e820.nr_map = 0;
		add_memory_region(0, LOWMEMSIZE(), E820_RAM);
		add_memory_region(HIGH_MEMORY, mem_size << 10, E820_RAM);
  	}
	printk(KERN_INFO "BIOS-provided physical RAM map:\n");
	print_memory_map(who);
} /* setup_memory_region */


static void __init parse_mem_cmdline (char ** cmdline_p)
{
	char c = ' ', *to = command_line, *from = COMMAND_LINE;
	int len = 0;
	int usermem = 0;

	/* Save unparsed command line copy for /proc/cmdline */
	memcpy(saved_command_line, COMMAND_LINE, COMMAND_LINE_SIZE);
	saved_command_line[COMMAND_LINE_SIZE-1] = '\0';

	for (;;) {
		/*
		 * "mem=nopentium" disables the 4MB page tables.
		 * "mem=XXX[kKmM]" defines a memory region from HIGH_MEM
		 * to <mem>, overriding the bios size.
		 * "mem=XXX[KkmM]@XXX[KkmM]" defines a memory region from
		 * <start> to <start>+<mem>, overriding the bios size.
		 */
		if (c == ' ' && !memcmp(from, "mem=", 4)) {
			if (to != command_line)
				to--;
			if (!memcmp(from+4, "nopentium", 9)) {
				from += 9+4;
				clear_bit(X86_FEATURE_PSE, boot_cpu_data.x86_capability);
			} else if (!memcmp(from+4, "exactmap", 8)) {
				from += 8+4;
				e820.nr_map = 0;
				usermem = 1;
			} else {
				/* If the user specifies memory size, we
				 * blow away any automatically generated
				 * size
				 */
				unsigned long long start_at, mem_size;
 
				if (usermem == 0) {
					/* first time in: zap the whitelist
					 * and reinitialize it with the
					 * standard low-memory region.
					 */
					e820.nr_map = 0;
					usermem = 1;
					add_memory_region(0, LOWMEMSIZE(), E820_RAM);
				}
				mem_size = memparse(from+4, &from);
				if (*from == '@')
					start_at = memparse(from+1, &from);
				else {
					start_at = HIGH_MEMORY;
					mem_size -= HIGH_MEMORY;
					usermem=0;
				}
				add_memory_region(start_at, mem_size, E820_RAM);
			}
		}
		/*
		 * highmem=size forces highmem to be exactly 'size' bytes.
		 * This works even on boxes that have no highmem otherwise.
		 * This also works to reduce highmem size on bigger boxes.
		 */
		if (c == ' ' && !memcmp(from, "highmem=", 8))
			highmem_pages = memparse(from+8, &from) >> PAGE_SHIFT;
	
		c = *(from++);
		if (!c)
			break;
		if (COMMAND_LINE_SIZE <= ++len)
			break;
		*(to++) = c;
	}
	*to = '\0';
	*cmdline_p = command_line;
	if (usermem) {
		printk(KERN_INFO "user-defined physical RAM map:\n");
		print_memory_map("user");
	}
}

void __init setup_arch(char **cmdline_p)
{
	unsigned long bootmap_size, low_mem_size;
	unsigned long start_pfn, max_low_pfn;
	int i;

#ifdef CONFIG_VISWS
	visws_get_board_type_and_rev();
#endif

 	ROOT_DEV = to_kdev_t(ORIG_ROOT_DEV);
 	drive_info = DRIVE_INFO;
 	screen_info = SCREEN_INFO;
	apm_info.bios = APM_BIOS_INFO;
	if( SYS_DESC_TABLE.length != 0 ) {
		MCA_bus = SYS_DESC_TABLE.table[3] &0x2;
		machine_id = SYS_DESC_TABLE.table[0];
		machine_submodel_id = SYS_DESC_TABLE.table[1];
		BIOS_revision = SYS_DESC_TABLE.table[2];
	}
	aux_device_present = AUX_DEVICE_INFO;

#ifdef CONFIG_BLK_DEV_RAM
	rd_image_start = RAMDISK_FLAGS & RAMDISK_IMAGE_START_MASK;
	rd_prompt = ((RAMDISK_FLAGS & RAMDISK_PROMPT_FLAG) != 0);
	rd_doload = ((RAMDISK_FLAGS & RAMDISK_LOAD_FLAG) != 0);
#endif
	setup_memory_region();

	if (!MOUNT_ROOT_RDONLY)
		root_mountflags &= ~MS_RDONLY;
	init_mm.start_code = (unsigned long) &_text;
	init_mm.end_code = (unsigned long) &_etext;
	init_mm.end_data = (unsigned long) &_edata;
	init_mm.brk = (unsigned long) &_end;

	code_resource.start = virt_to_phys(&_text);
	code_resource.end = virt_to_phys(&_etext)-1;
	data_resource.start = virt_to_phys(&_etext);
	data_resource.end = virt_to_phys(&_edata)-1;

	parse_mem_cmdline(cmdline_p);

#define PFN_UP(x)	(((x) + PAGE_SIZE-1) >> PAGE_SHIFT)
#define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
#define PFN_PHYS(x)	((x) << PAGE_SHIFT)

/*
 * Reserved space for vmalloc and iomap - defined in asm/page.h
 */
#define MAXMEM_PFN	PFN_DOWN(MAXMEM)
#define MAX_NONPAE_PFN	(1 << 20)

	/*
	 * partially used pages are not usable - thus
	 * we are rounding upwards:
	 */
	start_pfn = PFN_UP(__pa(&_end));

	/*
	 * Find the highest page frame number we have available
	 */
	max_pfn = 0;
	for (i = 0; i < e820.nr_map; i++) {
		unsigned long start, end;
		/* RAM? */
		if (e820.map[i].type != E820_RAM)
			continue;
		start = PFN_UP(e820.map[i].addr);
		end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
		if (start >= end)
			continue;
		if (end > max_pfn)
			max_pfn = end;
	}

	/*
	 * Determine low and high memory ranges:
	 */
	max_low_pfn = max_pfn;
	if (max_low_pfn > MAXMEM_PFN) {
		if (highmem_pages == -1)
			highmem_pages = max_pfn - MAXMEM_PFN;
		if (highmem_pages + MAXMEM_PFN < max_pfn)
			max_pfn = MAXMEM_PFN + highmem_pages;
		if (highmem_pages + MAXMEM_PFN > max_pfn) {
			printk("only %luMB highmem pages available, ignoring highmem size of %uMB.\n", pages_to_mb(max_pfn - MAXMEM_PFN), pages_to_mb(highmem_pages));
			highmem_pages = 0;
		}
		max_low_pfn = MAXMEM_PFN;
#ifndef CONFIG_HIGHMEM
		/* Maximum memory usable is what is directly addressable */
		printk(KERN_WARNING "Warning only %ldMB will be used.\n",
					MAXMEM>>20);
		if (max_pfn > MAX_NONPAE_PFN)
			printk(KERN_WARNING "Use a PAE enabled kernel.\n");
		else
			printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
		max_pfn = MAXMEM_PFN;
#else /* !CONFIG_HIGHMEM */
#ifndef CONFIG_X86_PAE
		if (max_pfn > MAX_NONPAE_PFN) {
			max_pfn = MAX_NONPAE_PFN;
			printk(KERN_WARNING "Warning only 4GB will be used.\n");
			printk(KERN_WARNING "Use a PAE enabled kernel.\n");
		}
#endif /* !CONFIG_X86_PAE */
#endif /* !CONFIG_HIGHMEM */
	} else {
		if (highmem_pages == -1)
			highmem_pages = 0;
#if CONFIG_HIGHMEM
		if (highmem_pages >= max_pfn) {
			printk(KERN_ERR "highmem size specified (%uMB) is bigger than pages available (%luMB)!.\n", pages_to_mb(highmem_pages), pages_to_mb(max_pfn));
			highmem_pages = 0;
		}
		if (highmem_pages) {
			if (max_low_pfn-highmem_pages < 64*1024*1024/PAGE_SIZE){
				printk(KERN_ERR "highmem size %uMB results in smaller than 64MB lowmem, ignoring it.\n", pages_to_mb(highmem_pages));
				highmem_pages = 0;
			}
			max_low_pfn -= highmem_pages;
		}
#else
		if (highmem_pages)
			printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n");
#endif
	}

#ifdef CONFIG_HIGHMEM
	highstart_pfn = highend_pfn = max_pfn;
	if (max_pfn > max_low_pfn) {
		highstart_pfn = max_low_pfn;
	}
	printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
		pages_to_mb(highend_pfn - highstart_pfn));
#endif
	printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
			pages_to_mb(max_low_pfn));
	/*
	 * Initialize the boot-time allocator (with low memory only):
	 */
	bootmap_size = init_bootmem(start_pfn, max_low_pfn);

	/*
	 * Register fully available low RAM pages with the bootmem allocator.
	 */
	for (i = 0; i < e820.nr_map; i++) {
		unsigned long curr_pfn, last_pfn, size;
 		/*
		 * Reserve usable low memory
		 */
		if (e820.map[i].type != E820_RAM)
			continue;
		/*
		 * We are rounding up the start address of usable memory:
		 */
		curr_pfn = PFN_UP(e820.map[i].addr);
		if (curr_pfn >= max_low_pfn)
			continue;
		/*
		 * ... and at the end of the usable range downwards:
		 */
		last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);

		if (last_pfn > max_low_pfn)
			last_pfn = max_low_pfn;

		/*
		 * .. finally, did all the rounding and playing
		 * around just make the area go away?
		 */
		if (last_pfn <= curr_pfn)
			continue;

		size = last_pfn - curr_pfn;
		free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
	}
	/*
	 * Reserve the bootmem bitmap itself as well. We do this in two
	 * steps (first step was init_bootmem()) because this catches
	 * the (very unlikely) case of us accidentally initializing the
	 * bootmem allocator with an invalid RAM area.
	 */
	reserve_bootmem(HIGH_MEMORY, (PFN_PHYS(start_pfn) +
			 bootmap_size + PAGE_SIZE-1) - (HIGH_MEMORY));

	/*
	 * reserve physical page 0 - it's a special BIOS page on many boxes,
	 * enabling clean reboots, SMP operation, laptop functions.
	 */
	reserve_bootmem(0, PAGE_SIZE);

#ifdef CONFIG_SMP
	/*
	 * But first pinch a few for the stack/trampoline stuff
	 * FIXME: Don't need the extra page at 4K, but need to fix
	 * trampoline before removing it. (see the GDT stuff)
	 */
	reserve_bootmem(PAGE_SIZE, PAGE_SIZE);
#endif
#ifdef CONFIG_ACPI_SLEEP
	/*
	 * Reserve low memory region for sleep support.
	 */
	acpi_reserve_bootmem();
#endif
#ifdef CONFIG_X86_LOCAL_APIC
	/*
	 * Find and reserve possible boot-time SMP configuration:
	 */
	find_smp_config();
#endif
#ifdef CONFIG_BLK_DEV_INITRD
	if (LOADER_TYPE && INITRD_START) {
		if (INITRD_START + INITRD_SIZE <= (max_low_pfn << PAGE_SHIFT)) {
			reserve_bootmem(INITRD_START, INITRD_SIZE);
			initrd_start =
				INITRD_START ? INITRD_START + PAGE_OFFSET : 0;
			initrd_end = initrd_start+INITRD_SIZE;
		}
		else {
			printk(KERN_ERR "initrd extends beyond end of memory "
			    "(0x%08lx > 0x%08lx)\ndisabling initrd\n",
			    INITRD_START + INITRD_SIZE,
			    max_low_pfn << PAGE_SHIFT);
			initrd_start = 0;
		}
	}
#endif

	/*
	 * NOTE: before this point _nobody_ is allowed to allocate
	 * any memory using the bootmem allocator.
	 */

#ifdef CONFIG_SMP
	smp_alloc_memory(); /* AP processor realmode stacks in low memory*/
#endif
	paging_init();
#ifdef CONFIG_ACPI_BOOT
	/*
	 * Initialize the ACPI boot-time table parser (gets the RSDP and SDT).
	 * Must do this after paging_init (due to reliance on fixmap, and thus
	 * the bootmem allocator) but before get_smp_config (to allow parsing
	 * of MADT).
	 */
	acpi_boot_init(*cmdline_p);
#endif
#ifdef CONFIG_X86_LOCAL_APIC
	/*
	 * get boot-time SMP configuration:
	 */
	if (smp_found_config)
		get_smp_config();
#endif


	/*
	 * Request address space for all standard RAM and ROM resources
	 * and also for regions reported as reserved by the e820.
	 */
	probe_roms();
	for (i = 0; i < e820.nr_map; i++) {
		struct resource *res;
		if (e820.map[i].addr + e820.map[i].size > 0x100000000ULL)
			continue;
		res = alloc_bootmem_low(sizeof(struct resource));
		switch (e820.map[i].type) {
		case E820_RAM:	res->name = "System RAM"; break;
		case E820_ACPI:	res->name = "ACPI Tables"; break;
		case E820_NVS:	res->name = "ACPI Non-volatile Storage"; break;
		default:	res->name = "reserved";
		}
		res->start = e820.map[i].addr;
		res->end = res->start + e820.map[i].size - 1;
		res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
		request_resource(&iomem_resource, res);
		if (e820.map[i].type == E820_RAM) {
			/*
			 *  We dont't know which RAM region contains kernel data,
			 *  so we try it repeatedly and let the resource manager
			 *  test it.
			 */
			request_resource(res, &code_resource);
			request_resource(res, &data_resource);
		}
	}
	request_resource(&iomem_resource, &vram_resource);

	/* request I/O space for devices used on all i[345]86 PCs */
	for (i = 0; i < STANDARD_IO_RESOURCES; i++)
		request_resource(&ioport_resource, standard_io_resources+i);

	/* Tell the PCI layer not to allocate too close to the RAM area.. */
	low_mem_size = ((max_low_pfn << PAGE_SHIFT) + 0xfffff) & ~0xfffff;
	if (low_mem_size > pci_mem_start)
		pci_mem_start = low_mem_size;

#ifdef CONFIG_VT
#if defined(CONFIG_VGA_CONSOLE)
	conswitchp = &vga_con;
#elif defined(CONFIG_DUMMY_CONSOLE)
	conswitchp = &dummy_con;
#endif
#endif
	dmi_scan_machine();
}

static int cachesize_override __initdata = -1;
static int __init cachesize_setup(char *str)
{
	get_option (&str, &cachesize_override);
	return 1;
}
__setup("cachesize=", cachesize_setup);