setup.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

		struct e820entry *pbios; /* pointer to original bios entry */
		unsigned long long addr; /* address for this change point */
	};
	static struct change_member change_point_list[2*E820MAX];
	static struct change_member *change_point[2*E820MAX];
	static struct e820entry *overlap_list[E820MAX];
	static struct e820entry new_bios[E820MAX];
	struct change_member *change_tmp;
	unsigned long current_type, last_type;
	unsigned long long last_addr;
	int chgidx, still_changing;
	int overlap_entries;
	int new_bios_entry;
	int old_nr, new_nr;
	int i;

	/*
		Visually we're performing the following (1,2,3,4 = memory types)...

		Sample memory map (w/overlaps):
		   ____22__________________
		   ______________________4_
		   ____1111________________
		   _44_____________________
		   11111111________________
		   ____________________33__
		   ___________44___________
		   __________33333_________
		   ______________22________
		   ___________________2222_
		   _________111111111______
		   _____________________11_
		   _________________4______

		Sanitized equivalent (no overlap):
		   1_______________________
		   _44_____________________
		   ___1____________________
		   ____22__________________
		   ______11________________
		   _________1______________
		   __________3_____________
		   ___________44___________
		   _____________33_________
		   _______________2________
		   ________________1_______
		   _________________4______
		   ___________________2____
		   ____________________33__
		   ______________________4_
	*/

	/* if there's only one memory region, don't bother */
	if (*pnr_map < 2)
		return -1;

	old_nr = *pnr_map;

	/* bail out if we find any unreasonable addresses in bios map */
	for (i=0; i<old_nr; i++)
		if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr)
			return -1;

	/* create pointers for initial change-point information (for sorting) */
	for (i=0; i < 2*old_nr; i++)
		change_point[i] = &change_point_list[i];

	/* record all known change-points (starting and ending addresses) */
	chgidx = 0;
	for (i=0; i < old_nr; i++)	{
		change_point[chgidx]->addr = biosmap[i].addr;
		change_point[chgidx++]->pbios = &biosmap[i];
		change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
		change_point[chgidx++]->pbios = &biosmap[i];
	}

	/* sort change-point list by memory addresses (low -> high) */
	still_changing = 1;
	while (still_changing)	{
		still_changing = 0;
		for (i=1; i < 2*old_nr; i++)  {
			/* if <current_addr> > <last_addr>, swap */
			/* or, if current=<start_addr> & last=<end_addr>, swap */
			if ((change_point[i]->addr < change_point[i-1]->addr) ||
				((change_point[i]->addr == change_point[i-1]->addr) &&
				 (change_point[i]->addr == change_point[i]->pbios->addr) &&
				 (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
			   )
			{
				change_tmp = change_point[i];
				change_point[i] = change_point[i-1];
				change_point[i-1] = change_tmp;
				still_changing=1;
			}
		}
	}

	/* create a new bios memory map, removing overlaps */
	overlap_entries=0;	 /* number of entries in the overlap table */
	new_bios_entry=0;	 /* index for creating new bios map entries */
	last_type = 0;		 /* start with undefined memory type */
	last_addr = 0;		 /* start with 0 as last starting address */
	/* loop through change-points, determining affect on the new bios map */
	for (chgidx=0; chgidx < 2*old_nr; chgidx++)
	{
		/* keep track of all overlapping bios entries */
		if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
		{
			/* add map entry to overlap list (> 1 entry implies an overlap) */
			overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
		}
		else
		{
			/* remove entry from list (order independent, so swap with last) */
			for (i=0; i<overlap_entries; i++)
			{
				if (overlap_list[i] == change_point[chgidx]->pbios)
					overlap_list[i] = overlap_list[overlap_entries-1];
			}
			overlap_entries--;
		}
		/* if there are overlapping entries, decide which "type" to use */
		/* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
		current_type = 0;
		for (i=0; i<overlap_entries; i++)
			if (overlap_list[i]->type > current_type)
				current_type = overlap_list[i]->type;
		/* continue building up new bios map based on this information */
		if (current_type != last_type)	{
			if (last_type != 0)	 {
				new_bios[new_bios_entry].size =
					change_point[chgidx]->addr - last_addr;
				/* move forward only if the new size was non-zero */
				if (new_bios[new_bios_entry].size != 0)
					if (++new_bios_entry >= E820MAX)
						break; 	/* no more space left for new bios entries */
			}
			if (current_type != 0)	{
				new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
				new_bios[new_bios_entry].type = current_type;
				last_addr=change_point[chgidx]->addr;
			}
			last_type = current_type;
		}
	}
	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;
}

#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
unsigned char eddnr;
struct edd_info edd[EDDMAXNR];
/**
 * copy_edd() - Copy the BIOS EDD information
 *              from empty_zero_page into a safe place.
 *
 */
static inline void copy_edd(void)
{
     eddnr = EDD_NR;
     memcpy(edd, EDD_BUF, sizeof(edd));
}
#else
#define copy_edd() do {} while (0)
#endif

/*
 * 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 */

int allowsysinfo = 1;

static void __init parse_cmdline_early (char ** cmdline_p)
{
	char c = ' ', *to = command_line, *from = COMMAND_LINE;
	int len = 0;
	int userdef = 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 (;;) {
		if (c != ' ')
			goto nextchar;
		/*
		 * "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 (!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);
				set_bit(X86_FEATURE_PSE, &disabled_x86_caps);
			} else if (!memcmp(from+4, "exactmap", 8)) {
				from += 8+4;
				e820.nr_map = 0;
				userdef = 1;
			} else {
				/* If the user specifies memory size, we
				 * limit the BIOS-provided memory map to
				 * that size. exactmap can be used to specify
				 * the exact map. mem=number can be used to
				 * trim the existing memory map.
				 */
				unsigned long long start_at, mem_size;
 
				mem_size = memparse(from+4, &from);
				if (*from == '@') {
					start_at = memparse(from+1, &from);
					add_memory_region(start_at, mem_size, E820_RAM);
				} else {
					limit_regions(mem_size);
					userdef=1;
				}
			}
		}

		/* "noht" disables HyperThreading (2 logical cpus per Xeon) */
		else if (!memcmp(from, "noht", 4)) { 
			disable_x86_ht = 1;
			set_bit(X86_FEATURE_HT, disabled_x86_caps);
		}

		/* "acpismp=force" forces parsing and use of the ACPI SMP table */
		else if (!memcmp(from, "acpismp=force", 13))
			enable_acpi_smp_table = 1;

		else if (!memcmp(from, "nosysinfo", 9))
			allowsysinfo = 0;

		/*
		 * 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.
		 */
		else if (!memcmp(from, "highmem=", 8))
			highmem_pages = memparse(from+8, &from) >> PAGE_SHIFT;
nextchar:
		c = *(from++);
		if (!c)
			break;
		if (COMMAND_LINE_SIZE <= ++len)
			break;
		*(to++) = c;
	}
	*to = '\0';
	*cmdline_p = command_line;
	if (userdef) {
		printk(KERN_INFO "user-defined physical RAM map:\n");
		print_memory_map("user");
	}
}

#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)

/*
 * Find the highest page frame number we have available
 */
static void __init find_max_pfn(void)
{
	int i;

	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:
 */
static unsigned long __init find_max_low_pfn(void)
{
	unsigned long max_low_pfn;

	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");
#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
	}

	return max_low_pfn;
}

/*
 * Register fully available low RAM pages with the bootmem allocator.
 */
static void __init register_bootmem_low_pages(unsigned long max_low_pfn)
{
	int i;

	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));
	}
}

static unsigned long __init setup_memory(void)
{
	unsigned long bootmap_size, start_pfn, max_low_pfn;

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

	find_max_pfn();

	max_low_pfn = find_max_low_pfn();