e820.c

来自「linux-2.4.29操作系统的源码」· C语言 代码 · 共 609 行 · 第 1/2 页

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	*/

	/* 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 start = biosmap->addr;
		unsigned long size = biosmap->size;
		unsigned 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.
		 * 
		 * This should be removed on Hammer which is supposed to not
		 * have non e820 covered ISA mappings there, but I had some strange
		 * problems so it stays for now.  -AK
		 */
		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;
}

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");
	e820_print_map(who);
}

extern char command_line[], saved_command_line[];
extern int fallback_aper_order;
extern int iommu_setup(char *opt);

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

		/*
		 * mem=XXX[kKmM] limits kernel memory to XXX+1MB
		 *
		 * It would be more logical to count from 0 instead of from
		 * HIGH_MEMORY, but we keep that for now for i386 compatibility. -AK
		 */
		if (!memcmp(from, "mem=", 4)) {
			/* 
			 * No support for custom mapping like i386.
			 * The reason is that we need to read the e820 map
			 * anyways to handle the ACPI mappings in the 
			 * direct map.
			 * Also on x86-64 there should be always a good e820
			 * map. This is only an upper limit, you cannot force
			 * usage of memory not in e820.
					 */
			end_user_pfn = memparse(from+4, &from) + HIGH_MEMORY;
			end_user_pfn >>= PAGE_SHIFT;
		}
#ifdef CONFIG_GART_IOMMU 
		else if (!memcmp(from,"iommu=",6)) { 
			iommu_setup(from+6); 
		} 	
#endif
#ifdef	CONFIG_SMP
		/*
		 * If the BIOS enumerates physical processors before logical,
		 * maxcpus=N at enumeration-time can be used to disable HT.
		 */
		else if (!memcmp(from, "maxcpus=", 8)) {
			extern unsigned int max_cpus;

			max_cpus = simple_strtoul(from + 8, NULL, 0);
		}
#endif

#ifdef	CONFIG_ACPI_BOOT
 		else if (!memcmp(from, "acpi=off", 8))
  			disable_acpi();

		/* acpi=strict disables out-of-spec workarounds */
		else if (!memcmp(from, "acpi=strict", 11)) {
			acpi_strict = 1;
		}

		else if (!memcmp(from, "pci=noacpi", 10))
			acpi_disable_pci();
		else if (!memcmp(from, "acpi=noirq", 10))
			acpi_noirq_set();
		else if (!memcmp(from, "acpi_sci=edge", 13))
			acpi_sci_flags.trigger =  1;
		else if (!memcmp(from, "acpi_sci=level", 14))
			acpi_sci_flags.trigger = 3;
		else if (!memcmp(from, "acpi_sci=high", 13))
			acpi_sci_flags.polarity = 1;
		else if (!memcmp(from, "acpi_sci=low", 12))
			acpi_sci_flags.polarity = 3;
#endif
		else if (!memcmp(from,"maxcpus=0",9)) {
			disable_ioapic_setup();
			apic_disabled = 1;
		}
		
		else if (!memcmp(from, "noapic", 6)) 
			disable_ioapic_setup();
		else if (!memcmp(from, "nolocalapic", 11) || !memcmp(from,"nolapic",7))
			apic_disabled = 1;
		else if (!memcmp(from,"apic",4)) {
			extern int ioapic_force;
			ioapic_force = 1;
			skip_ioapic_setup = 0;
		}
		
	next:
		c = *(from++);
		if (!c)
			break;
		if (COMMAND_LINE_SIZE <= ++len)
			break;
		*(to++) = c;
	}
	*to = '\0';
	*cmdline_p = command_line;
}