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/arch/i386/mm/init.c

https://bitbucket.org/evzijst/gittest
C | 696 lines | 488 code | 101 blank | 107 comment | 80 complexity | 0c6a75ebfed4470df2666db455d7d1c2 MD5 | raw file
  1/*
  2 *  linux/arch/i386/mm/init.c
  3 *
  4 *  Copyright (C) 1995  Linus Torvalds
  5 *
  6 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
  7 */
  8
  9#include <linux/config.h>
 10#include <linux/module.h>
 11#include <linux/signal.h>
 12#include <linux/sched.h>
 13#include <linux/kernel.h>
 14#include <linux/errno.h>
 15#include <linux/string.h>
 16#include <linux/types.h>
 17#include <linux/ptrace.h>
 18#include <linux/mman.h>
 19#include <linux/mm.h>
 20#include <linux/hugetlb.h>
 21#include <linux/swap.h>
 22#include <linux/smp.h>
 23#include <linux/init.h>
 24#include <linux/highmem.h>
 25#include <linux/pagemap.h>
 26#include <linux/bootmem.h>
 27#include <linux/slab.h>
 28#include <linux/proc_fs.h>
 29#include <linux/efi.h>
 30
 31#include <asm/processor.h>
 32#include <asm/system.h>
 33#include <asm/uaccess.h>
 34#include <asm/pgtable.h>
 35#include <asm/dma.h>
 36#include <asm/fixmap.h>
 37#include <asm/e820.h>
 38#include <asm/apic.h>
 39#include <asm/tlb.h>
 40#include <asm/tlbflush.h>
 41#include <asm/sections.h>
 42
 43unsigned int __VMALLOC_RESERVE = 128 << 20;
 44
 45DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 46unsigned long highstart_pfn, highend_pfn;
 47
 48static int noinline do_test_wp_bit(void);
 49
 50/*
 51 * Creates a middle page table and puts a pointer to it in the
 52 * given global directory entry. This only returns the gd entry
 53 * in non-PAE compilation mode, since the middle layer is folded.
 54 */
 55static pmd_t * __init one_md_table_init(pgd_t *pgd)
 56{
 57	pud_t *pud;
 58	pmd_t *pmd_table;
 59		
 60#ifdef CONFIG_X86_PAE
 61	pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 62	set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
 63	pud = pud_offset(pgd, 0);
 64	if (pmd_table != pmd_offset(pud, 0)) 
 65		BUG();
 66#else
 67	pud = pud_offset(pgd, 0);
 68	pmd_table = pmd_offset(pud, 0);
 69#endif
 70
 71	return pmd_table;
 72}
 73
 74/*
 75 * Create a page table and place a pointer to it in a middle page
 76 * directory entry.
 77 */
 78static pte_t * __init one_page_table_init(pmd_t *pmd)
 79{
 80	if (pmd_none(*pmd)) {
 81		pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 82		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
 83		if (page_table != pte_offset_kernel(pmd, 0))
 84			BUG();	
 85
 86		return page_table;
 87	}
 88	
 89	return pte_offset_kernel(pmd, 0);
 90}
 91
 92/*
 93 * This function initializes a certain range of kernel virtual memory 
 94 * with new bootmem page tables, everywhere page tables are missing in
 95 * the given range.
 96 */
 97
 98/*
 99 * NOTE: The pagetables are allocated contiguous on the physical space 
100 * so we can cache the place of the first one and move around without 
101 * checking the pgd every time.
102 */
103static void __init page_table_range_init (unsigned long start, unsigned long end, pgd_t *pgd_base)
104{
105	pgd_t *pgd;
106	pud_t *pud;
107	pmd_t *pmd;
108	int pgd_idx, pmd_idx;
109	unsigned long vaddr;
110
111	vaddr = start;
112	pgd_idx = pgd_index(vaddr);
113	pmd_idx = pmd_index(vaddr);
114	pgd = pgd_base + pgd_idx;
115
116	for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
117		if (pgd_none(*pgd)) 
118			one_md_table_init(pgd);
119		pud = pud_offset(pgd, vaddr);
120		pmd = pmd_offset(pud, vaddr);
121		for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end); pmd++, pmd_idx++) {
122			if (pmd_none(*pmd)) 
123				one_page_table_init(pmd);
124
125			vaddr += PMD_SIZE;
126		}
127		pmd_idx = 0;
128	}
129}
130
131static inline int is_kernel_text(unsigned long addr)
132{
133	if (addr >= PAGE_OFFSET && addr <= (unsigned long)__init_end)
134		return 1;
135	return 0;
136}
137
138/*
139 * This maps the physical memory to kernel virtual address space, a total 
140 * of max_low_pfn pages, by creating page tables starting from address 
141 * PAGE_OFFSET.
142 */
143static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
144{
145	unsigned long pfn;
146	pgd_t *pgd;
147	pmd_t *pmd;
148	pte_t *pte;
149	int pgd_idx, pmd_idx, pte_ofs;
150
151	pgd_idx = pgd_index(PAGE_OFFSET);
152	pgd = pgd_base + pgd_idx;
153	pfn = 0;
154
155	for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
156		pmd = one_md_table_init(pgd);
157		if (pfn >= max_low_pfn)
158			continue;
159		for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD && pfn < max_low_pfn; pmd++, pmd_idx++) {
160			unsigned int address = pfn * PAGE_SIZE + PAGE_OFFSET;
161
162			/* Map with big pages if possible, otherwise create normal page tables. */
163			if (cpu_has_pse) {
164				unsigned int address2 = (pfn + PTRS_PER_PTE - 1) * PAGE_SIZE + PAGE_OFFSET + PAGE_SIZE-1;
165
166				if (is_kernel_text(address) || is_kernel_text(address2))
167					set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
168				else
169					set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE));
170				pfn += PTRS_PER_PTE;
171			} else {
172				pte = one_page_table_init(pmd);
173
174				for (pte_ofs = 0; pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn; pte++, pfn++, pte_ofs++) {
175						if (is_kernel_text(address))
176							set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
177						else
178							set_pte(pte, pfn_pte(pfn, PAGE_KERNEL));
179				}
180			}
181		}
182	}
183}
184
185static inline int page_kills_ppro(unsigned long pagenr)
186{
187	if (pagenr >= 0x70000 && pagenr <= 0x7003F)
188		return 1;
189	return 0;
190}
191
192extern int is_available_memory(efi_memory_desc_t *);
193
194static inline int page_is_ram(unsigned long pagenr)
195{
196	int i;
197	unsigned long addr, end;
198
199	if (efi_enabled) {
200		efi_memory_desc_t *md;
201
202		for (i = 0; i < memmap.nr_map; i++) {
203			md = &memmap.map[i];
204			if (!is_available_memory(md))
205				continue;
206			addr = (md->phys_addr+PAGE_SIZE-1) >> PAGE_SHIFT;
207			end = (md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT)) >> PAGE_SHIFT;
208
209			if ((pagenr >= addr) && (pagenr < end))
210				return 1;
211		}
212		return 0;
213	}
214
215	for (i = 0; i < e820.nr_map; i++) {
216
217		if (e820.map[i].type != E820_RAM)	/* not usable memory */
218			continue;
219		/*
220		 *	!!!FIXME!!! Some BIOSen report areas as RAM that
221		 *	are not. Notably the 640->1Mb area. We need a sanity
222		 *	check here.
223		 */
224		addr = (e820.map[i].addr+PAGE_SIZE-1) >> PAGE_SHIFT;
225		end = (e820.map[i].addr+e820.map[i].size) >> PAGE_SHIFT;
226		if  ((pagenr >= addr) && (pagenr < end))
227			return 1;
228	}
229	return 0;
230}
231
232#ifdef CONFIG_HIGHMEM
233pte_t *kmap_pte;
234pgprot_t kmap_prot;
235
236#define kmap_get_fixmap_pte(vaddr)					\
237	pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), vaddr), (vaddr)), (vaddr))
238
239static void __init kmap_init(void)
240{
241	unsigned long kmap_vstart;
242
243	/* cache the first kmap pte */
244	kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
245	kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
246
247	kmap_prot = PAGE_KERNEL;
248}
249
250static void __init permanent_kmaps_init(pgd_t *pgd_base)
251{
252	pgd_t *pgd;
253	pud_t *pud;
254	pmd_t *pmd;
255	pte_t *pte;
256	unsigned long vaddr;
257
258	vaddr = PKMAP_BASE;
259	page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
260
261	pgd = swapper_pg_dir + pgd_index(vaddr);
262	pud = pud_offset(pgd, vaddr);
263	pmd = pmd_offset(pud, vaddr);
264	pte = pte_offset_kernel(pmd, vaddr);
265	pkmap_page_table = pte;	
266}
267
268void __init one_highpage_init(struct page *page, int pfn, int bad_ppro)
269{
270	if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) {
271		ClearPageReserved(page);
272		set_bit(PG_highmem, &page->flags);
273		set_page_count(page, 1);
274		__free_page(page);
275		totalhigh_pages++;
276	} else
277		SetPageReserved(page);
278}
279
280#ifndef CONFIG_DISCONTIGMEM
281static void __init set_highmem_pages_init(int bad_ppro)
282{
283	int pfn;
284	for (pfn = highstart_pfn; pfn < highend_pfn; pfn++)
285		one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro);
286	totalram_pages += totalhigh_pages;
287}
288#else
289extern void set_highmem_pages_init(int);
290#endif /* !CONFIG_DISCONTIGMEM */
291
292#else
293#define kmap_init() do { } while (0)
294#define permanent_kmaps_init(pgd_base) do { } while (0)
295#define set_highmem_pages_init(bad_ppro) do { } while (0)
296#endif /* CONFIG_HIGHMEM */
297
298unsigned long long __PAGE_KERNEL = _PAGE_KERNEL;
299unsigned long long __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;
300
301#ifndef CONFIG_DISCONTIGMEM
302#define remap_numa_kva() do {} while (0)
303#else
304extern void __init remap_numa_kva(void);
305#endif
306
307static void __init pagetable_init (void)
308{
309	unsigned long vaddr;
310	pgd_t *pgd_base = swapper_pg_dir;
311
312#ifdef CONFIG_X86_PAE
313	int i;
314	/* Init entries of the first-level page table to the zero page */
315	for (i = 0; i < PTRS_PER_PGD; i++)
316		set_pgd(pgd_base + i, __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
317#endif
318
319	/* Enable PSE if available */
320	if (cpu_has_pse) {
321		set_in_cr4(X86_CR4_PSE);
322	}
323
324	/* Enable PGE if available */
325	if (cpu_has_pge) {
326		set_in_cr4(X86_CR4_PGE);
327		__PAGE_KERNEL |= _PAGE_GLOBAL;
328		__PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
329	}
330
331	kernel_physical_mapping_init(pgd_base);
332	remap_numa_kva();
333
334	/*
335	 * Fixed mappings, only the page table structure has to be
336	 * created - mappings will be set by set_fixmap():
337	 */
338	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
339	page_table_range_init(vaddr, 0, pgd_base);
340
341	permanent_kmaps_init(pgd_base);
342
343#ifdef CONFIG_X86_PAE
344	/*
345	 * Add low memory identity-mappings - SMP needs it when
346	 * starting up on an AP from real-mode. In the non-PAE
347	 * case we already have these mappings through head.S.
348	 * All user-space mappings are explicitly cleared after
349	 * SMP startup.
350	 */
351	pgd_base[0] = pgd_base[USER_PTRS_PER_PGD];
352#endif
353}
354
355#if defined(CONFIG_PM_DISK) || defined(CONFIG_SOFTWARE_SUSPEND)
356/*
357 * Swap suspend & friends need this for resume because things like the intel-agp
358 * driver might have split up a kernel 4MB mapping.
359 */
360char __nosavedata swsusp_pg_dir[PAGE_SIZE]
361	__attribute__ ((aligned (PAGE_SIZE)));
362
363static inline void save_pg_dir(void)
364{
365	memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
366}
367#else
368static inline void save_pg_dir(void)
369{
370}
371#endif
372
373void zap_low_mappings (void)
374{
375	int i;
376
377	save_pg_dir();
378
379	/*
380	 * Zap initial low-memory mappings.
381	 *
382	 * Note that "pgd_clear()" doesn't do it for
383	 * us, because pgd_clear() is a no-op on i386.
384	 */
385	for (i = 0; i < USER_PTRS_PER_PGD; i++)
386#ifdef CONFIG_X86_PAE
387		set_pgd(swapper_pg_dir+i, __pgd(1 + __pa(empty_zero_page)));
388#else
389		set_pgd(swapper_pg_dir+i, __pgd(0));
390#endif
391	flush_tlb_all();
392}
393
394static int disable_nx __initdata = 0;
395u64 __supported_pte_mask = ~_PAGE_NX;
396
397/*
398 * noexec = on|off
399 *
400 * Control non executable mappings.
401 *
402 * on      Enable
403 * off     Disable
404 */
405void __init noexec_setup(const char *str)
406{
407	if (!strncmp(str, "on",2) && cpu_has_nx) {
408		__supported_pte_mask |= _PAGE_NX;
409		disable_nx = 0;
410	} else if (!strncmp(str,"off",3)) {
411		disable_nx = 1;
412		__supported_pte_mask &= ~_PAGE_NX;
413	}
414}
415
416int nx_enabled = 0;
417#ifdef CONFIG_X86_PAE
418
419static void __init set_nx(void)
420{
421	unsigned int v[4], l, h;
422
423	if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
424		cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
425		if ((v[3] & (1 << 20)) && !disable_nx) {
426			rdmsr(MSR_EFER, l, h);
427			l |= EFER_NX;
428			wrmsr(MSR_EFER, l, h);
429			nx_enabled = 1;
430			__supported_pte_mask |= _PAGE_NX;
431		}
432	}
433}
434
435/*
436 * Enables/disables executability of a given kernel page and
437 * returns the previous setting.
438 */
439int __init set_kernel_exec(unsigned long vaddr, int enable)
440{
441	pte_t *pte;
442	int ret = 1;
443
444	if (!nx_enabled)
445		goto out;
446
447	pte = lookup_address(vaddr);
448	BUG_ON(!pte);
449
450	if (!pte_exec_kernel(*pte))
451		ret = 0;
452
453	if (enable)
454		pte->pte_high &= ~(1 << (_PAGE_BIT_NX - 32));
455	else
456		pte->pte_high |= 1 << (_PAGE_BIT_NX - 32);
457	__flush_tlb_all();
458out:
459	return ret;
460}
461
462#endif
463
464/*
465 * paging_init() sets up the page tables - note that the first 8MB are
466 * already mapped by head.S.
467 *
468 * This routines also unmaps the page at virtual kernel address 0, so
469 * that we can trap those pesky NULL-reference errors in the kernel.
470 */
471void __init paging_init(void)
472{
473#ifdef CONFIG_X86_PAE
474	set_nx();
475	if (nx_enabled)
476		printk("NX (Execute Disable) protection: active\n");
477#endif
478
479	pagetable_init();
480
481	load_cr3(swapper_pg_dir);
482
483#ifdef CONFIG_X86_PAE
484	/*
485	 * We will bail out later - printk doesn't work right now so
486	 * the user would just see a hanging kernel.
487	 */
488	if (cpu_has_pae)
489		set_in_cr4(X86_CR4_PAE);
490#endif
491	__flush_tlb_all();
492
493	kmap_init();
494}
495
496/*
497 * Test if the WP bit works in supervisor mode. It isn't supported on 386's
498 * and also on some strange 486's (NexGen etc.). All 586+'s are OK. This
499 * used to involve black magic jumps to work around some nasty CPU bugs,
500 * but fortunately the switch to using exceptions got rid of all that.
501 */
502
503static void __init test_wp_bit(void)
504{
505	printk("Checking if this processor honours the WP bit even in supervisor mode... ");
506
507	/* Any page-aligned address will do, the test is non-destructive */
508	__set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_READONLY);
509	boot_cpu_data.wp_works_ok = do_test_wp_bit();
510	clear_fixmap(FIX_WP_TEST);
511
512	if (!boot_cpu_data.wp_works_ok) {
513		printk("No.\n");
514#ifdef CONFIG_X86_WP_WORKS_OK
515		panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!");
516#endif
517	} else {
518		printk("Ok.\n");
519	}
520}
521
522static void __init set_max_mapnr_init(void)
523{
524#ifdef CONFIG_HIGHMEM
525	num_physpages = highend_pfn;
526#else
527	num_physpages = max_low_pfn;
528#endif
529#ifndef CONFIG_DISCONTIGMEM
530	max_mapnr = num_physpages;
531#endif
532}
533
534static struct kcore_list kcore_mem, kcore_vmalloc; 
535
536void __init mem_init(void)
537{
538	extern int ppro_with_ram_bug(void);
539	int codesize, reservedpages, datasize, initsize;
540	int tmp;
541	int bad_ppro;
542
543#ifndef CONFIG_DISCONTIGMEM
544	if (!mem_map)
545		BUG();
546#endif
547	
548	bad_ppro = ppro_with_ram_bug();
549
550#ifdef CONFIG_HIGHMEM
551	/* check that fixmap and pkmap do not overlap */
552	if (PKMAP_BASE+LAST_PKMAP*PAGE_SIZE >= FIXADDR_START) {
553		printk(KERN_ERR "fixmap and kmap areas overlap - this will crash\n");
554		printk(KERN_ERR "pkstart: %lxh pkend: %lxh fixstart %lxh\n",
555				PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE, FIXADDR_START);
556		BUG();
557	}
558#endif
559 
560	set_max_mapnr_init();
561
562#ifdef CONFIG_HIGHMEM
563	high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
564#else
565	high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
566#endif
567
568	/* this will put all low memory onto the freelists */
569	totalram_pages += free_all_bootmem();
570
571	reservedpages = 0;
572	for (tmp = 0; tmp < max_low_pfn; tmp++)
573		/*
574		 * Only count reserved RAM pages
575		 */
576		if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp)))
577			reservedpages++;
578
579	set_highmem_pages_init(bad_ppro);
580
581	codesize =  (unsigned long) &_etext - (unsigned long) &_text;
582	datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
583	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
584
585	kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT); 
586	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START, 
587		   VMALLOC_END-VMALLOC_START);
588
589	printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n",
590		(unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
591		num_physpages << (PAGE_SHIFT-10),
592		codesize >> 10,
593		reservedpages << (PAGE_SHIFT-10),
594		datasize >> 10,
595		initsize >> 10,
596		(unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
597	       );
598
599#ifdef CONFIG_X86_PAE
600	if (!cpu_has_pae)
601		panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!");
602#endif
603	if (boot_cpu_data.wp_works_ok < 0)
604		test_wp_bit();
605
606	/*
607	 * Subtle. SMP is doing it's boot stuff late (because it has to
608	 * fork idle threads) - but it also needs low mappings for the
609	 * protected-mode entry to work. We zap these entries only after
610	 * the WP-bit has been tested.
611	 */
612#ifndef CONFIG_SMP
613	zap_low_mappings();
614#endif
615}
616
617kmem_cache_t *pgd_cache;
618kmem_cache_t *pmd_cache;
619
620void __init pgtable_cache_init(void)
621{
622	if (PTRS_PER_PMD > 1) {
623		pmd_cache = kmem_cache_create("pmd",
624					PTRS_PER_PMD*sizeof(pmd_t),
625					PTRS_PER_PMD*sizeof(pmd_t),
626					0,
627					pmd_ctor,
628					NULL);
629		if (!pmd_cache)
630			panic("pgtable_cache_init(): cannot create pmd cache");
631	}
632	pgd_cache = kmem_cache_create("pgd",
633				PTRS_PER_PGD*sizeof(pgd_t),
634				PTRS_PER_PGD*sizeof(pgd_t),
635				0,
636				pgd_ctor,
637				PTRS_PER_PMD == 1 ? pgd_dtor : NULL);
638	if (!pgd_cache)
639		panic("pgtable_cache_init(): Cannot create pgd cache");
640}
641
642/*
643 * This function cannot be __init, since exceptions don't work in that
644 * section.  Put this after the callers, so that it cannot be inlined.
645 */
646static int noinline do_test_wp_bit(void)
647{
648	char tmp_reg;
649	int flag;
650
651	__asm__ __volatile__(
652		"	movb %0,%1	\n"
653		"1:	movb %1,%0	\n"
654		"	xorl %2,%2	\n"
655		"2:			\n"
656		".section __ex_table,\"a\"\n"
657		"	.align 4	\n"
658		"	.long 1b,2b	\n"
659		".previous		\n"
660		:"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
661		 "=q" (tmp_reg),
662		 "=r" (flag)
663		:"2" (1)
664		:"memory");
665	
666	return flag;
667}
668
669void free_initmem(void)
670{
671	unsigned long addr;
672
673	addr = (unsigned long)(&__init_begin);
674	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
675		ClearPageReserved(virt_to_page(addr));
676		set_page_count(virt_to_page(addr), 1);
677		memset((void *)addr, 0xcc, PAGE_SIZE);
678		free_page(addr);
679		totalram_pages++;
680	}
681	printk (KERN_INFO "Freeing unused kernel memory: %dk freed\n", (__init_end - __init_begin) >> 10);
682}
683
684#ifdef CONFIG_BLK_DEV_INITRD
685void free_initrd_mem(unsigned long start, unsigned long end)
686{
687	if (start < end)
688		printk (KERN_INFO "Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
689	for (; start < end; start += PAGE_SIZE) {
690		ClearPageReserved(virt_to_page(start));
691		set_page_count(virt_to_page(start), 1);
692		free_page(start);
693		totalram_pages++;
694	}
695}
696#endif