- Linus: more PageDirty / swapcache handling

[davej-history.git] / arch / ppc / mm / init.c

/*
 *  $Id: init.c,v 1.195 1999/10/15 16:39:39 cort Exp $
 *
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 *    Copyright (C) 1996 Paul Mackerras
 *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#include <linux/config.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/openpic.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#ifdef CONFIG_BLK_DEV_INITRD
#include <linux/blk.h>          /* for initrd_* */
#endif

#include <asm/pgalloc.h>
#include <asm/prom.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/residual.h>
#include <asm/uaccess.h>
#ifdef CONFIG_8xx
#include <asm/8xx_immap.h>
#include <asm/mpc8xx.h>
#endif
#ifdef CONFIG_8260
#include <asm/immap_8260.h>
#include <asm/mpc8260.h>
#endif
#include <asm/smp.h>
#include <asm/bootx.h>
#include <asm/machdep.h>
#include <asm/setup.h>
#include <asm/amigahw.h>
#include <asm/gemini.h>

#include "mem_pieces.h"

#if defined(CONFIG_4xx)
#include "4xx_tlb.h"
#endif

#define MAX_LOW_MEM     (640 << 20)

#define PGTOKB(pages)   (((pages) * PAGE_SIZE) >> 10)

int prom_trashed;
atomic_t next_mmu_context;
unsigned long *end_of_DRAM;
unsigned long total_memory;
unsigned long total_lowmem;
int mem_init_done;
int init_bootmem_done;
int boot_mapsize;
unsigned long totalram_pages;
unsigned long totalhigh_pages;
extern pgd_t swapper_pg_dir[];
extern char _start[], _end[];
extern char etext[], _stext[];
extern char __init_begin, __init_end;
extern char __prep_begin, __prep_end;
extern char __chrp_begin, __chrp_end;
extern char __pmac_begin, __pmac_end;
extern char __apus_begin, __apus_end;
extern char __openfirmware_begin, __openfirmware_end;
struct device_node *memory_node;
unsigned long ioremap_base;
unsigned long ioremap_bot;
unsigned long avail_start;
extern int num_memory;
extern struct mem_info memory[];
extern boot_infos_t *boot_infos;
extern unsigned int rtas_data, rtas_size;
#ifndef CONFIG_SMP
struct pgtable_cache_struct quicklists;
#endif
#ifdef CONFIG_HIGHMEM
pte_t *kmap_pte;
pgprot_t kmap_prot;
#endif

void MMU_init(void);
static void *MMU_get_page(void);
unsigned long prep_find_end_of_memory(void);
unsigned long pmac_find_end_of_memory(void);
unsigned long apus_find_end_of_memory(void);
unsigned long gemini_find_end_of_memory(void);
extern unsigned long find_end_of_memory(void);
#ifdef CONFIG_8xx
unsigned long m8xx_find_end_of_memory(void);
#endif /* CONFIG_8xx */
#ifdef CONFIG_4xx
unsigned long oak_find_end_of_memory(void);
#endif
#ifdef CONFIG_8260
unsigned long m8260_find_end_of_memory(void);
#endif /* CONFIG_8260 */
static void mapin_ram(void);
void map_page(unsigned long va, unsigned long pa, int flags);
void set_phys_avail(struct mem_pieces *mp);
extern void die_if_kernel(char *,struct pt_regs *,long);

extern char _start[], _end[];
extern char _stext[], etext[];
extern struct task_struct *current_set[NR_CPUS];

struct mem_pieces phys_mem;
char *klimit = _end;
struct mem_pieces phys_avail;

PTE *Hash, *Hash_end;
unsigned long Hash_size, Hash_mask;
#if !defined(CONFIG_4xx) && !defined(CONFIG_8xx)
unsigned long _SDR1;
static void hash_init(void);

union ubat {                    /* BAT register values to be loaded */
        BAT     bat;
#ifdef CONFIG_PPC64BRIDGE
        u64     word[2];
#else
        u32     word[2];
#endif  
} BATS[4][2];                   /* 4 pairs of IBAT, DBAT */

struct batrange {               /* stores address ranges mapped by BATs */
        unsigned long start;
        unsigned long limit;
        unsigned long phys;
} bat_addrs[4];

/*
 * Return PA for this VA if it is mapped by a BAT, or 0
 */
static inline unsigned long v_mapped_by_bats(unsigned long va)
{
        int b;
        for (b = 0; b < 4; ++b)
                if (va >= bat_addrs[b].start && va < bat_addrs[b].limit)
                        return bat_addrs[b].phys + (va - bat_addrs[b].start);
        return 0;
}

/*
 * Return VA for a given PA or 0 if not mapped
 */
static inline unsigned long p_mapped_by_bats(unsigned long pa)
{
        int b;
        for (b = 0; b < 4; ++b)
                if (pa >= bat_addrs[b].phys
                    && pa < (bat_addrs[b].limit-bat_addrs[b].start)
                              +bat_addrs[b].phys)
                        return bat_addrs[b].start+(pa-bat_addrs[b].phys);
        return 0;
}

#else /* CONFIG_4xx || CONFIG_8xx */
#define v_mapped_by_bats(x)     (0UL)
#define p_mapped_by_bats(x)     (0UL)
#endif /* !CONFIG_4xx && !CONFIG_8xx */

/*
 * this tells the system to map all of ram with the segregs
 * (i.e. page tables) instead of the bats.
 * -- Cort
 */
int __map_without_bats;

/* max amount of RAM to use */
unsigned long __max_memory;

void __bad_pte(pmd_t *pmd)
{
        printk("Bad pmd in pte_alloc: %08lx\n", pmd_val(*pmd));
        pmd_val(*pmd) = (unsigned long) BAD_PAGETABLE;
}

pte_t *get_pte_slow(pmd_t *pmd, unsigned long offset)
{
        pte_t *pte;

        if (pmd_none(*pmd)) {
                if (!mem_init_done)
                        pte = (pte_t *) MMU_get_page();
                else if ((pte = (pte_t *) __get_free_page(GFP_KERNEL)))
                        clear_page(pte);
                if (pte) {
                        pmd_val(*pmd) = (unsigned long)pte;
                        return pte + offset;
                }
                pmd_val(*pmd) = (unsigned long)BAD_PAGETABLE;
                return NULL;
        }
        if (pmd_bad(*pmd)) {
                __bad_pte(pmd);
                return NULL;
        }
        return (pte_t *) pmd_page(*pmd) + offset;
}

int do_check_pgt_cache(int low, int high)
{
        int freed = 0;
        if(pgtable_cache_size > high) {
                do {
                        if(pgd_quicklist)
                                free_pgd_slow(get_pgd_fast()), freed++;
                        if(pmd_quicklist)
                                free_pmd_slow(get_pmd_fast()), freed++;
                        if(pte_quicklist)
                                free_pte_slow(get_pte_fast()), freed++;
                } while(pgtable_cache_size > low);
        }
        return freed;
}

/*
 * BAD_PAGE is the page that is used for page faults when linux
 * is out-of-memory. Older versions of linux just did a
 * do_exit(), but using this instead means there is less risk
 * for a process dying in kernel mode, possibly leaving a inode
 * unused etc..
 *
 * BAD_PAGETABLE is the accompanying page-table: it is initialized
 * to point to BAD_PAGE entries.
 *
 * ZERO_PAGE is a special page that is used for zero-initialized
 * data and COW.
 */
pte_t *empty_bad_page_table;

pte_t * __bad_pagetable(void)
{
        clear_page(empty_bad_page_table);
        return empty_bad_page_table;
}

void *empty_bad_page;

pte_t __bad_page(void)
{
        clear_page(empty_bad_page);
        return pte_mkdirty(mk_pte_phys(__pa(empty_bad_page), PAGE_SHARED));
}

void show_mem(void)
{
        int i,free = 0,total = 0,reserved = 0;
        int shared = 0, cached = 0;
        struct task_struct *p;
        int highmem = 0;

        printk("Mem-info:\n");
        show_free_areas();
        printk("Free swap:       %6dkB\n",nr_swap_pages<<(PAGE_SHIFT-10));
        i = max_mapnr;
        while (i-- > 0) {
                total++;
                if (PageHighMem(mem_map+i))
                        highmem++;
                if (PageReserved(mem_map+i))
                        reserved++;
                else if (PageSwapCache(mem_map+i))
                        cached++;
                else if (!page_count(mem_map+i))
                        free++;
                else
                        shared += atomic_read(&mem_map[i].count) - 1;
        }
        printk("%d pages of RAM\n",total);
        printk("%d pages of HIGHMEM\n", highmem);
        printk("%d free pages\n",free);
        printk("%d reserved pages\n",reserved);
        printk("%d pages shared\n",shared);
        printk("%d pages swap cached\n",cached);
        printk("%d pages in page table cache\n",(int)pgtable_cache_size);
        show_buffers();
        printk("%-8s %3s %8s %8s %8s %9s %8s", "Process", "Pid",
               "Ctx", "Ctx<<4", "Last Sys", "pc", "task");
#ifdef CONFIG_SMP
        printk(" %3s", "CPU");
#endif /* CONFIG_SMP */
        printk("\n");
        for_each_task(p)
        {
                printk("%-8.8s %3d %8ld %8ld %8ld %c%08lx %08lx ",
                       p->comm,p->pid,
                       (p->mm)?p->mm->context:0,
                       (p->mm)?(p->mm->context<<4):0,
                       p->thread.last_syscall,
                       (p->thread.regs)?user_mode(p->thread.regs) ? 'u' : 'k' : '?',
                       (p->thread.regs)?p->thread.regs->nip:0,
                       (ulong)p);
                {
                        int iscur = 0;
#ifdef CONFIG_SMP
                        printk("%3d ", p->processor);
                        if ( (p->processor != NO_PROC_ID) &&
                             (p == current_set[p->processor]) )
                        {
                                iscur = 1;
                                printk("current");
                        }
#else
                        if ( p == current )
                        {
                                iscur = 1;
                                printk("current");
                        }
                        
                        if ( p == last_task_used_math )
                        {
                                if ( iscur )
                                        printk(",");
                                printk("last math");
                        }                       
#endif /* CONFIG_SMP */
                        printk("\n");
                }
        }
}

void si_meminfo(struct sysinfo *val)
{
        int i;

        i = max_mapnr;
        val->totalram = 0;
        val->sharedram = 0;
        val->freeram = nr_free_pages();
        val->bufferram = atomic_read(&buffermem_pages);
        while (i-- > 0)  {
                if (PageReserved(mem_map+i))
                        continue;
                val->totalram++;
                if (!atomic_read(&mem_map[i].count))
                        continue;
                val->sharedram += atomic_read(&mem_map[i].count) - 1;
        }
        val->totalhigh = totalhigh_pages;
        val->freehigh = nr_free_highpages();
        val->mem_unit = PAGE_SIZE;
}

void *
ioremap(unsigned long addr, unsigned long size)
{
        return __ioremap(addr, size, _PAGE_NO_CACHE);
}

void *
__ioremap(unsigned long addr, unsigned long size, unsigned long flags)
{
        unsigned long p, v, i;

        /*
         * Choose an address to map it to.
         * Once the vmalloc system is running, we use it.
         * Before then, we map addresses >= ioremap_base
         * virt == phys; for addresses below this we use
         * space going down from ioremap_base (ioremap_bot
         * records where we're up to).
         */
        p = addr & PAGE_MASK;
        size = PAGE_ALIGN(addr + size) - p;

        /*
         * If the address lies within the first 16 MB, assume it's in ISA
         * memory space
         */
        if (p < 16*1024*1024)
            p += _ISA_MEM_BASE;

        /*
         * Don't allow anybody to remap normal RAM that we're using.
         * mem_init() sets high_memory so only do the check after that.
         */
        if ( mem_init_done && (p < virt_to_phys(high_memory)) )
        {
                printk("__ioremap(): phys addr %0lx is RAM lr %p\n", p,
                       __builtin_return_address(0));
                return NULL;
        }

        if (size == 0)
                return NULL;

        /*
         * Is it already mapped?  Perhaps overlapped by a previous
         * BAT mapping.  If the whole area is mapped then we're done,
         * otherwise remap it since we want to keep the virt addrs for
         * each request contiguous.
         *
         * We make the assumption here that if the bottom and top
         * of the range we want are mapped then it's mapped to the
         * same virt address (and this is contiguous).
         *  -- Cort
         */
        if ((v = p_mapped_by_bats(p)) /*&& p_mapped_by_bats(p+size-1)*/ )
                goto out;
        
        if (mem_init_done) {
                struct vm_struct *area;
                area = get_vm_area(size, VM_IOREMAP);
                if (area == 0)
                        return NULL;
                v = VMALLOC_VMADDR(area->addr);
        } else {
                if (p >= ioremap_base)
                        v = p;
                else
                        v = (ioremap_bot -= size);
        }

        if ((flags & _PAGE_PRESENT) == 0)
                flags |= pgprot_val(PAGE_KERNEL);
        if (flags & (_PAGE_NO_CACHE | _PAGE_WRITETHRU))
                flags |= _PAGE_GUARDED;

        /*
         * Is it a candidate for a BAT mapping?
         */
        for (i = 0; i < size; i += PAGE_SIZE)
                map_page(v+i, p+i, flags);
out:
        return (void *) (v + (addr & ~PAGE_MASK));
}

void iounmap(void *addr)
{
        if (addr > high_memory && (unsigned long) addr < ioremap_bot)
                vfree((void *) (PAGE_MASK & (unsigned long) addr));
}

unsigned long iopa(unsigned long addr)
{
        unsigned long pa;
        pmd_t *pd;
        pte_t *pg;

        /* Check the BATs */
        pa = v_mapped_by_bats(addr);
        if (pa)
                return pa;

        /* Do we have a page table? */
        if (init_mm.pgd == NULL)
                return 0;

        /* Use upper 10 bits of addr to index the first level map */
        pd = (pmd_t *) (init_mm.pgd + (addr >> PGDIR_SHIFT));
        if (pmd_none(*pd))
                return 0;

        /* Use middle 10 bits of addr to index the second-level map */
        pg = pte_offset(pd, addr);
        return (pte_val(*pg) & PAGE_MASK) | (addr & ~PAGE_MASK);
}

void
map_page(unsigned long va, unsigned long pa, int flags)
{
        pmd_t *pd, oldpd;
        pte_t *pg;

        /* Use upper 10 bits of VA to index the first level map */
        pd = pmd_offset(pgd_offset_k(va), va);
        oldpd = *pd;
        /* Use middle 10 bits of VA to index the second-level map */
        pg = pte_alloc(pd, va);
        if (pmd_none(oldpd) && mem_init_done)
                set_pgdir(va, *(pgd_t *)pd);
        set_pte(pg, mk_pte_phys(pa & PAGE_MASK, __pgprot(flags)));
        if (mem_init_done)
                flush_hash_page(0, va);
}

#ifndef CONFIG_8xx
/*
 * TLB flushing:
 *
 *  - flush_tlb_all() flushes all processes TLBs
 *  - flush_tlb_mm(mm) flushes the specified mm context TLB's
 *  - flush_tlb_page(vma, vmaddr) flushes one page
 *  - flush_tlb_range(mm, start, end) flushes a range of pages
 *
 * since the hardware hash table functions as an extension of the
 * tlb as far as the linux tables are concerned, flush it too.
 *    -- Cort
 */

/*
 * Flush all tlb/hash table entries (except perhaps for those
 * mapping RAM starting at PAGE_OFFSET, since they never change).
 */
void
local_flush_tlb_all(void)
{
#ifdef CONFIG_PPC64BRIDGE
        /* XXX this assumes that the vmalloc arena starts no lower than
         * 0xd0000000 on 64-bit machines. */
        flush_hash_segments(0xd, 0xffffff);
#else
        __clear_user(Hash, Hash_size);
        _tlbia();
#ifdef CONFIG_SMP
        smp_send_tlb_invalidate(0);
#endif /* CONFIG_SMP */
#endif /* CONFIG_PPC64BRIDGE */
}

/*
 * Flush all the (user) entries for the address space described
 * by mm.  We can't rely on mm->mmap describing all the entries
 * that might be in the hash table.
 */
void
local_flush_tlb_mm(struct mm_struct *mm)
{
        mm->context = NO_CONTEXT;
        if (mm == current->mm)
                activate_mm(mm, mm);
#ifdef CONFIG_SMP
        smp_send_tlb_invalidate(0);
#endif  
}

void
local_flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr)
{
        if (vmaddr < TASK_SIZE)
                flush_hash_page(vma->vm_mm->context, vmaddr);
        else
                flush_hash_page(0, vmaddr);
#ifdef CONFIG_SMP
        smp_send_tlb_invalidate(0);
#endif  
}


/*
 * for each page addr in the range, call MMU_invalidate_page()
 * if the range is very large and the hash table is small it might be
 * faster to do a search of the hash table and just invalidate pages
 * that are in the range but that's for study later.
 * -- Cort
 */
void
local_flush_tlb_range(struct mm_struct *mm, unsigned long start, unsigned long end)
{
        start &= PAGE_MASK;

        if (end - start > 20 * PAGE_SIZE)
        {
                flush_tlb_mm(mm);
                return;
        }

        for (; start < end && start < TASK_SIZE; start += PAGE_SIZE)
        {
                flush_hash_page(mm->context, start);
        }
#ifdef CONFIG_SMP
        smp_send_tlb_invalidate(0);
#endif  
}

/*
 * The context counter has overflowed.
 * We set mm->context to NO_CONTEXT for all mm's in the system.
 * We assume we can get to all mm's by looking as tsk->mm for
 * all tasks in the system.
 */
void
mmu_context_overflow(void)
{
        struct task_struct *tsk;

        printk(KERN_DEBUG "mmu_context_overflow\n");
        read_lock(&tasklist_lock);
        for_each_task(tsk) {
                if (tsk->mm)
                        tsk->mm->context = NO_CONTEXT;
        }
        read_unlock(&tasklist_lock);
        flush_hash_segments(0x10, 0xffffff);
#ifdef CONFIG_SMP
        smp_send_tlb_invalidate(0);
#endif  
        atomic_set(&next_mmu_context, 0);
        /* make sure current always has a context */
        current->mm->context = MUNGE_CONTEXT(atomic_inc_return(&next_mmu_context));
        /* The PGD is only a placeholder.  It is only used on
         * 8xx processors.
         */
        set_context(current->mm->context, current->mm->pgd);
}
#endif /* CONFIG_8xx */

void flush_page_to_ram(struct page *page)
{
        unsigned long vaddr = (unsigned long) kmap(page);
        __flush_page_to_ram(vaddr);
        kunmap(page);
}

#if !defined(CONFIG_4xx) && !defined(CONFIG_8xx)
static void get_mem_prop(char *, struct mem_pieces *);

#if defined(CONFIG_ALL_PPC)
/*
 * Read in a property describing some pieces of memory.
 */

static void __init get_mem_prop(char *name, struct mem_pieces *mp)
{
        struct reg_property *rp;
        int s;

        rp = (struct reg_property *) get_property(memory_node, name, &s);
        if (rp == NULL) {
                printk(KERN_ERR "error: couldn't get %s property on /memory\n",
                       name);
                abort();
        }
        mp->n_regions = s / sizeof(mp->regions[0]);
        memcpy(mp->regions, rp, s);

        /* Make sure the pieces are sorted. */
        mem_pieces_sort(mp);
        mem_pieces_coalesce(mp);
}
#endif /* CONFIG_ALL_PPC */

/*
 * Set up one of the I/D BAT (block address translation) register pairs.
 * The parameters are not checked; in particular size must be a power
 * of 2 between 128k and 256M.
 */
void __init setbat(int index, unsigned long virt, unsigned long phys,
       unsigned int size, int flags)
{
        unsigned int bl;
        int wimgxpp;
        union ubat *bat = BATS[index];

        bl = (size >> 17) - 1;
        if ((_get_PVR() >> 16) != 1) {
                /* 603, 604, etc. */
                /* Do DBAT first */
                wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
                                   | _PAGE_COHERENT | _PAGE_GUARDED);
                wimgxpp |= (flags & _PAGE_RW)? BPP_RW: BPP_RX;
                bat[1].word[0] = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
                bat[1].word[1] = phys | wimgxpp;
#ifndef CONFIG_KGDB /* want user access for breakpoints */
                if (flags & _PAGE_USER)
#endif
                        bat[1].bat.batu.vp = 1;
                if (flags & _PAGE_GUARDED) {
                        /* G bit must be zero in IBATs */
                        bat[0].word[0] = bat[0].word[1] = 0;
                } else {
                        /* make IBAT same as DBAT */
                        bat[0] = bat[1];
                }
        } else {
                /* 601 cpu */
                if (bl > BL_8M)
                        bl = BL_8M;
                wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
                                   | _PAGE_COHERENT);
                wimgxpp |= (flags & _PAGE_RW)?
                        ((flags & _PAGE_USER)? PP_RWRW: PP_RWXX): PP_RXRX;
                bat->word[0] = virt | wimgxpp | 4;      /* Ks=0, Ku=1 */
                bat->word[1] = phys | bl | 0x40;        /* V=1 */
        }

        bat_addrs[index].start = virt;
        bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1;
        bat_addrs[index].phys = phys;
}

#define IO_PAGE (_PAGE_NO_CACHE | _PAGE_GUARDED | _PAGE_RW)
#ifdef CONFIG_SMP
#define RAM_PAGE (_PAGE_RW|_PAGE_COHERENT)
#else
#define RAM_PAGE (_PAGE_RW)
#endif
#endif /* CONFIG_8xx */

/*
 * Map in all of physical memory starting at KERNELBASE.
 */
#define PAGE_KERNEL_RO  __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED)

static void __init mapin_ram(void)
{
        int i;
        unsigned long v, p, s, f;

#if !defined(CONFIG_4xx) && !defined(CONFIG_8xx) && !defined(CONFIG_POWER4)
        if (!__map_without_bats) {
                unsigned long tot, mem_base, bl, done;
                unsigned long max_size = (256<<20);
                unsigned long align;

                /* Set up BAT2 and if necessary BAT3 to cover RAM. */
                mem_base = __pa(KERNELBASE);

                /* Make sure we don't map a block larger than the
                   smallest alignment of the physical address. */
                /* alignment of mem_base */
                align = ~(mem_base-1) & mem_base;
                /* set BAT block size to MIN(max_size, align) */
                if (align && align < max_size)
                        max_size = align;

                tot = total_lowmem;
                for (bl = 128<<10; bl < max_size; bl <<= 1) {
                        if (bl * 2 > tot)
                                break;
                }

                setbat(2, KERNELBASE, mem_base, bl, RAM_PAGE);
                done = (unsigned long)bat_addrs[2].limit - KERNELBASE + 1;
                if ((done < tot) && !bat_addrs[3].limit) {
                        /* use BAT3 to cover a bit more */
                        tot -= done;
                        for (bl = 128<<10; bl < max_size; bl <<= 1)
                                if (bl * 2 > tot)
                                        break;
                        setbat(3, KERNELBASE+done, mem_base+done, bl, 
                               RAM_PAGE);
                }
        }
#endif /* !CONFIG_4xx && !CONFIG_8xx && !CONFIG_POWER4 */

        for (i = 0; i < phys_mem.n_regions; ++i) {
                v = (ulong)__va(phys_mem.regions[i].address);
                p = phys_mem.regions[i].address;
                if (p >= total_lowmem)
                        break;
                for (s = 0; s < phys_mem.regions[i].size; s += PAGE_SIZE) {
                        /* On the MPC8xx, we want the page shared so we
                         * don't get ASID compares on kernel space.
                         */
                        f = _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_SHARED;
#if defined(CONFIG_KGDB) || defined(CONFIG_XMON)
                        /* Allows stub to set breakpoints everywhere */
                        f |= _PAGE_RW | _PAGE_DIRTY | _PAGE_HWWRITE;
#else
                        if ((char *) v < _stext || (char *) v >= etext)
                                f |= _PAGE_RW | _PAGE_DIRTY | _PAGE_HWWRITE;
#ifndef CONFIG_8xx
                        else
                                /* On the powerpc (not 8xx), no user access
                                   forces R/W kernel access */
                                f |= _PAGE_USER;
#endif /* CONFIG_8xx */
#endif /* CONFIG_KGDB */
                        map_page(v, p, f);
                        v += PAGE_SIZE;
                        p += PAGE_SIZE;
                        if (p >= total_lowmem)
                                break;
                }
        }
}

/* In fact this is only called until mem_init is done. */
static void __init *MMU_get_page(void)
{
        void *p;

        if (mem_init_done) {
                p = (void *) __get_free_page(GFP_KERNEL);
        } else if (init_bootmem_done) {
                p = alloc_bootmem_pages(PAGE_SIZE);
        } else {
                p = mem_pieces_find(PAGE_SIZE, PAGE_SIZE);
        }
        if (p == 0)
                panic("couldn't get a page in MMU_get_page");
        __clear_user(p, PAGE_SIZE);
        return p;
}

static void free_sec(unsigned long start, unsigned long end, const char *name)
{
        unsigned long cnt = 0;

        while (start < end) {
                clear_bit(PG_reserved, &virt_to_page(start)->flags);
                set_page_count(virt_to_page(start), 1);
                free_page(start);
                cnt++;
                start += PAGE_SIZE;
        }
        if (cnt)
                printk(" %ldk %s", PGTOKB(cnt), name);
}

void free_initmem(void)
{
#define FREESEC(TYPE) \
        free_sec((unsigned long)(&__ ## TYPE ## _begin), \
                 (unsigned long)(&__ ## TYPE ## _end), \
                 #TYPE);

        printk ("Freeing unused kernel memory:");
        FREESEC(init);
        if (_machine != _MACH_Pmac)
                FREESEC(pmac);
        if (_machine != _MACH_chrp)
                FREESEC(chrp);
        if (_machine != _MACH_prep)
                FREESEC(prep);
        if (_machine != _MACH_apus)
                FREESEC(apus);
        if (!have_of)
                FREESEC(openfirmware);
        printk("\n");
#undef FREESEC
}

#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
        for (; start < end; start += PAGE_SIZE) {
                ClearPageReserved(virt_to_page(start));
                set_page_count(virt_to_page(start), 1);
                free_page(start);
                totalram_pages++;
        }
        printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
}
#endif

extern boot_infos_t *disp_bi;

/*
 * Do very early mm setup such as finding the size of memory
 * and setting up the hash table.
 * A lot of this is prep/pmac specific but a lot of it could
 * still be merged.
 * -- Cort
 */
#if defined(CONFIG_4xx)
void __init
MMU_init(void)
{
        /*
         * The Zone Protection Register (ZPR) defines how protection will
         * be applied to every page which is a member of a given zone. At
         * present, we utilize only two of the 4xx's zones. The first, zone
         * 0, is set at '00b and only allows access in supervisor-mode based
         * on the EX and WR bits. No user-mode access is allowed. The second,
         * zone 1, is set at '10b and in supervisor-mode allows access
         * without regard to the EX and WR bits. In user-mode, access is
         * allowed based on the EX and WR bits.
         */

        mtspr(SPRN_ZPR, 0x2aaaaaaa);

        /* Hardwire any TLB entries necessary here. */

        PPC4xx_tlb_pin(KERNELBASE, 0, TLB_PAGESZ(PAGESZ_16M), 1);

        /*
         * Find the top of physical memory and map all of it in starting
         * at KERNELBASE.
         */

        total_memory = total_lowmem = oak_find_end_of_memory();
        end_of_DRAM = __va(total_memory);
        mapin_ram();

        /*
         * Set up the real-mode cache parameters for the exception vector
         * handlers (which are run in real-mode).
         */

        mtspr(SPRN_DCWR, 0x00000000);   /* All caching is write-back */

        /*
         * Cache instruction and data space where the exception
         * vectors and the kernel live in real-mode.
         */

        mtspr(SPRN_DCCR, 0x80000000);   /* 128 MB of data space at 0x0. */
        mtspr(SPRN_ICCR, 0x80000000);   /* 128 MB of instr. space at 0x0. */
}
#else
        /* How about ppc_md.md_find_end_of_memory instead of these
         * ifdefs?  -- Dan.
         */
#ifdef CONFIG_BOOTX_TEXT
extern boot_infos_t *disp_bi;
#endif
void __init MMU_init(void)
{
        if ( ppc_md.progress ) ppc_md.progress("MMU:enter", 0x111);
#ifndef CONFIG_8xx
        if (have_of)
                total_memory = pmac_find_end_of_memory();
#ifdef CONFIG_APUS
        else if (_machine == _MACH_apus )
                total_memory = apus_find_end_of_memory();
#endif
#ifdef CONFIG_GEMINI    
        else if ( _machine == _MACH_gemini )
                total_memory = gemini_find_end_of_memory();
#endif /* CONFIG_GEMINI */
#if defined(CONFIG_8260)
        else
                total_memory = m8260_find_end_of_memory();
#else
        else /* prep */
                total_memory = prep_find_end_of_memory();
#endif

        total_lowmem = total_memory;
#ifdef CONFIG_HIGHMEM
        if (total_lowmem > MAX_LOW_MEM) {
                total_lowmem = MAX_LOW_MEM;
                mem_pieces_remove(&phys_avail, total_lowmem,
                                  total_memory - total_lowmem, 0);
        }
#endif /* CONFIG_HIGHMEM */
        end_of_DRAM = __va(total_lowmem);

        if ( ppc_md.progress ) ppc_md.progress("MMU:hash init", 0x300);
        hash_init();
#ifndef CONFIG_PPC64BRIDGE
        _SDR1 = __pa(Hash) | (Hash_mask >> 10);
#endif
        
        ioremap_base = 0xf8000000;

        if ( ppc_md.progress ) ppc_md.progress("MMU:mapin", 0x301);
        /* Map in all of RAM starting at KERNELBASE */
        mapin_ram();

#ifdef CONFIG_POWER4
        ioremap_base = ioremap_bot = 0xfffff000;
        isa_io_base = (unsigned long) ioremap(0xffd00000, 0x200000) + 0x100000;

#else /* CONFIG_POWER4 */
        /*
         * Setup the bat mappings we're going to load that cover
         * the io areas.  RAM was mapped by mapin_ram().
         * -- Cort
         */
        if ( ppc_md.progress ) ppc_md.progress("MMU:setbat", 0x302);
        switch (_machine) {
        case _MACH_prep:
                setbat(0, 0x80000000, 0x80000000, 0x10000000, IO_PAGE);
                setbat(1, 0xf0000000, 0xc0000000, 0x08000000, IO_PAGE);
                ioremap_base = 0xf0000000;
                break;
        case _MACH_chrp:
                setbat(0, 0xf8000000, 0xf8000000, 0x08000000, IO_PAGE);
#ifdef CONFIG_PPC64BRIDGE
                setbat(1, 0x80000000, 0xc0000000, 0x10000000, IO_PAGE);
#else
                setbat(1, 0x80000000, 0x80000000, 0x10000000, IO_PAGE);
                setbat(3, 0x90000000, 0x90000000, 0x10000000, IO_PAGE);
#endif
                break;
        case _MACH_Pmac:
                ioremap_base = 0xfe000000;
                break;
        case _MACH_apus:
                /* Map PPC exception vectors. */
                setbat(0, 0xfff00000, 0xfff00000, 0x00020000, RAM_PAGE);
                /* Map chip and ZorroII memory */
                setbat(1, zTwoBase,   0x00000000, 0x01000000, IO_PAGE);
                break;
        case _MACH_gemini:
                setbat(0, 0xf0000000, 0xf0000000, 0x10000000, IO_PAGE);
                setbat(1, 0x80000000, 0x80000000, 0x10000000, IO_PAGE);
                break;
        case _MACH_8260:
                /* Map the IMMR, plus anything else we can cover
                 * in that upper space according to the memory controller
                 * chip select mapping.  Grab another bunch of space
                 * below that for stuff we can't cover in the upper.
                 */
                setbat(0, 0xf0000000, 0xf0000000, 0x10000000, IO_PAGE);
                setbat(1, 0xe0000000, 0xe0000000, 0x10000000, IO_PAGE);
                ioremap_base = 0xe0000000;
                break;
        }
        ioremap_bot = ioremap_base;
#endif /* CONFIG_POWER4 */
#else /* CONFIG_8xx */

        total_memory = total_lowmem = m8xx_find_end_of_memory();
#ifdef CONFIG_HIGHMEM
        if (total_lowmem > MAX_LOW_MEM) {
                total_lowmem = MAX_LOW_MEM;
                mem_pieces_remove(&phys_avail, total_lowmem,
                                  total_memory - total_lowmem, 0);
        }
#endif /* CONFIG_HIGHMEM */
        end_of_DRAM = __va(total_lowmem);

        /* Map in all of RAM starting at KERNELBASE */
        mapin_ram();

        /* Now map in some of the I/O space that is generically needed
         * or shared with multiple devices.
         * All of this fits into the same 4Mbyte region, so it only
         * requires one page table page.
         */
        ioremap(IMAP_ADDR, IMAP_SIZE);
#ifdef CONFIG_MBX
        ioremap(NVRAM_ADDR, NVRAM_SIZE);
        ioremap(MBX_CSR_ADDR, MBX_CSR_SIZE);
        ioremap(PCI_CSR_ADDR, PCI_CSR_SIZE);

        /* Map some of the PCI/ISA I/O space to get the IDE interface.
        */
        ioremap(PCI_ISA_IO_ADDR, 0x4000);
        ioremap(PCI_IDE_ADDR, 0x4000);
#endif
#ifdef CONFIG_RPXLITE
        ioremap(RPX_CSR_ADDR, RPX_CSR_SIZE);
        ioremap(HIOX_CSR_ADDR, HIOX_CSR_SIZE);
#endif
#ifdef CONFIG_RPXCLASSIC
        ioremap(PCI_CSR_ADDR, PCI_CSR_SIZE);
        ioremap(RPX_CSR_ADDR, RPX_CSR_SIZE);
#endif
#endif /* CONFIG_8xx */
        if ( ppc_md.progress ) ppc_md.progress("MMU:exit", 0x211);
#ifdef CONFIG_BOOTX_TEXT
        /* Must be done last, or ppc_md.progress will die */
        if (_machine == _MACH_Pmac || _machine == _MACH_chrp)
                map_bootx_text();
#endif
}
#endif /* CONFIG_4xx */

/*
 * Initialize the bootmem system and give it all the memory we
 * have available.
 */
void __init do_init_bootmem(void)
{
        unsigned long start, size;
        int i;

        /*
         * Find an area to use for the bootmem bitmap.
         * We look for the first area which is at least
         * 128kB in length (128kB is enough for a bitmap
         * for 4GB of memory, using 4kB pages), plus 1 page
         * (in case the address isn't page-aligned).
         */
        start = 0;
        size = 0;
        for (i = 0; i < phys_avail.n_regions; ++i) {
                unsigned long a = phys_avail.regions[i].address;
                unsigned long s = phys_avail.regions[i].size;
                if (s <= size)
                        continue;
                start = a;
                size = s;
                if (s >= 33 * PAGE_SIZE)
                        break;
        }
        start = PAGE_ALIGN(start);

        boot_mapsize = init_bootmem(start >> PAGE_SHIFT,
                                    total_lowmem >> PAGE_SHIFT);

        /* remove the bootmem bitmap from the available memory */
        mem_pieces_remove(&phys_avail, start, boot_mapsize, 1);

        /* add everything in phys_avail into the bootmem map */
        for (i = 0; i < phys_avail.n_regions; ++i)
                free_bootmem(phys_avail.regions[i].address,
                             phys_avail.regions[i].size);

        init_bootmem_done = 1;
}

/*
 * paging_init() sets up the page tables - in fact we've already done this.
 */
void __init paging_init(void)
{
        unsigned long zones_size[MAX_NR_ZONES], i;

#ifdef CONFIG_HIGHMEM
        map_page(PKMAP_BASE, 0, 0);     /* XXX gross */
        pkmap_page_table = pte_offset(pmd_offset(pgd_offset_k(PKMAP_BASE), PKMAP_BASE), PKMAP_BASE);
        map_page(KMAP_FIX_BEGIN, 0, 0); /* XXX gross */
        kmap_pte = pte_offset(pmd_offset(pgd_offset_k(KMAP_FIX_BEGIN), KMAP_FIX_BEGIN), KMAP_FIX_BEGIN);
        kmap_prot = PAGE_KERNEL;
#endif /* CONFIG_HIGHMEM */

        /*
         * Grab some memory for bad_page and bad_pagetable to use.
         */
        empty_bad_page = alloc_bootmem_pages(PAGE_SIZE);
        empty_bad_page_table = alloc_bootmem_pages(PAGE_SIZE);

        /*
         * All pages are DMA-able so we put them all in the DMA zone.
         */
        zones_size[ZONE_DMA] = total_lowmem >> PAGE_SHIFT;
        for (i = 1; i < MAX_NR_ZONES; i++)
                zones_size[i] = 0;

#ifdef CONFIG_HIGHMEM
        zones_size[ZONE_HIGHMEM] = (total_memory - total_lowmem) >> PAGE_SHIFT;
#endif /* CONFIG_HIGHMEM */

        free_area_init(zones_size);
}

void __init mem_init(void)
{
        extern char *sysmap; 
        extern unsigned long sysmap_size;
        unsigned long addr;
        int codepages = 0;
        int datapages = 0;
        int initpages = 0;
#ifdef CONFIG_HIGHMEM
        unsigned long highmem_mapnr;

        highmem_mapnr = total_lowmem >> PAGE_SHIFT;
        highmem_start_page = mem_map + highmem_mapnr;
        max_mapnr = total_memory >> PAGE_SHIFT;
        totalram_pages += max_mapnr - highmem_mapnr;
#else
        max_mapnr = max_low_pfn;
#endif /* CONFIG_HIGHMEM */

        high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
        num_physpages = max_mapnr;      /* RAM is assumed contiguous */

        totalram_pages += free_all_bootmem();

#ifdef CONFIG_BLK_DEV_INITRD
        /* if we are booted from BootX with an initial ramdisk,
           make sure the ramdisk pages aren't reserved. */
        if (initrd_start) {
                for (addr = initrd_start; addr < initrd_end; addr += PAGE_SIZE)
                        clear_bit(PG_reserved, &virt_to_page(addr)->flags);
        }
#endif /* CONFIG_BLK_DEV_INITRD */

#if defined(CONFIG_ALL_PPC)     
        /* mark the RTAS pages as reserved */
        if ( rtas_data )
                for (addr = rtas_data; addr < PAGE_ALIGN(rtas_data+rtas_size) ;
                     addr += PAGE_SIZE)
                        SetPageReserved(virt_to_page(addr));
#endif /* defined(CONFIG_ALL_PPC) */
        if ( sysmap_size )
                for (addr = (unsigned long)sysmap;
                     addr < PAGE_ALIGN((unsigned long)sysmap+sysmap_size) ;
                     addr += PAGE_SIZE)
                        SetPageReserved(virt_to_page(addr));
        
        for (addr = PAGE_OFFSET; addr < (unsigned long)end_of_DRAM;
             addr += PAGE_SIZE) {
                if (!PageReserved(virt_to_page(addr)))
                        continue;
                if (addr < (ulong) etext)
                        codepages++;
                else if (addr >= (unsigned long)&__init_begin
                         && addr < (unsigned long)&__init_end)
                        initpages++;
                else if (addr < (ulong) klimit)
                        datapages++;
        }

#ifdef CONFIG_HIGHMEM
        {
                unsigned long pfn;

                for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
                        struct page *page = mem_map + pfn;

                        ClearPageReserved(page);
                        set_bit(PG_highmem, &page->flags);
                        atomic_set(&page->count, 1);
                        __free_page(page);
                        totalhigh_pages++;
                }
                totalram_pages += totalhigh_pages;
        }
#endif /* CONFIG_HIGHMEM */

        printk("Memory: %luk available (%dk kernel code, %dk data, %dk init, %ldk highmem)\n",
               (unsigned long)nr_free_pages()<< (PAGE_SHIFT-10),
               codepages<< (PAGE_SHIFT-10), datapages<< (PAGE_SHIFT-10),
               initpages<< (PAGE_SHIFT-10),
               (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)));
        mem_init_done = 1;
}

#if !defined(CONFIG_4xx) && !defined(CONFIG_8xx)
#if defined(CONFIG_ALL_PPC)
/*
 * On systems with Open Firmware, collect information about
 * physical RAM and which pieces are already in use.
 * At this point, we have (at least) the first 8MB mapped with a BAT.
 * Our text, data, bss use something over 1MB, starting at 0.
 * Open Firmware may be using 1MB at the 4MB point.
 */
unsigned long __init pmac_find_end_of_memory(void)
{
        unsigned long a, total;
        unsigned long ram_limit = 0xe0000000 - KERNELBASE;

        memory_node = find_devices("memory");
        if (memory_node == NULL) {
                printk(KERN_ERR "can't find memory node\n");
                abort();
        }

        /*
         * Find out where physical memory is, and check that it
         * starts at 0 and is contiguous.  It seems that RAM is
         * always physically contiguous on Power Macintoshes,
         * because MacOS can't cope if it isn't.
         *
         * Supporting discontiguous physical memory isn't hard,
         * it just makes the virtual <-> physical mapping functions
         * more complicated (or else you end up wasting space
         * in mem_map).
         */
        get_mem_prop("reg", &phys_mem);
        if (phys_mem.n_regions == 0)
                panic("No RAM??");
        a = phys_mem.regions[0].address;
        if (a != 0)
                panic("RAM doesn't start at physical address 0");
        if (__max_memory == 0 || __max_memory > ram_limit)
                __max_memory = ram_limit;
        if (phys_mem.regions[0].size >= __max_memory) {
                phys_mem.regions[0].size = __max_memory;
                phys_mem.n_regions = 1;
        }
        total = phys_mem.regions[0].size;
        
        if (phys_mem.n_regions > 1) {
                printk("RAM starting at 0x%x is not contiguous\n",
                       phys_mem.regions[1].address);
                printk("Using RAM from 0 to 0x%lx\n", total-1);
                phys_mem.n_regions = 1;
        }

        set_phys_avail(&phys_mem);

        return total;
}
#endif /* CONFIG_ALL_PPC */

#if defined(CONFIG_ALL_PPC)
/*
 * This finds the amount of physical ram and does necessary
 * setup for prep.  This is pretty architecture specific so
 * this will likely stay separate from the pmac.
 * -- Cort
 */
unsigned long __init prep_find_end_of_memory(void)
{
        unsigned long total;
        total = res->TotalMemory;

        if (total == 0 )
        {
                /*
                 * I need a way to probe the amount of memory if the residual
                 * data doesn't contain it. -- Cort
                 */
                printk("Ramsize from residual data was 0 -- Probing for value\n");
                total = 0x02000000;
                printk("Ramsize default to be %ldM\n", total>>20);
        }
        mem_pieces_append(&phys_mem, 0, total);
        set_phys_avail(&phys_mem);

        return (total);
}
#endif /* defined(CONFIG_ALL_PPC) */


#if defined(CONFIG_GEMINI)
unsigned long __init gemini_find_end_of_memory(void)
{
        unsigned long total;
        unsigned char reg;

        reg = readb(GEMINI_MEMCFG);
        total = ((1<<((reg & 0x7) - 1)) *
                 (8<<((reg >> 3) & 0x7)));
        total *= (1024*1024);
        phys_mem.regions[0].address = 0;
        phys_mem.regions[0].size = total;
        phys_mem.n_regions = 1;
        
        set_phys_avail(&phys_mem);
        return phys_mem.regions[0].size;
}
#endif /* defined(CONFIG_GEMINI) */

#ifdef CONFIG_8260
/*
 * Same hack as 8xx.
 */
unsigned long __init m8260_find_end_of_memory(void)
{
        bd_t    *binfo;
        extern unsigned char __res[];
        
        binfo = (bd_t *)__res;

        phys_mem.regions[0].address = 0;
        phys_mem.regions[0].size = binfo->bi_memsize;   
        phys_mem.n_regions = 1;
        
        set_phys_avail(&phys_mem);
        return phys_mem.regions[0].size;
}
#endif /* CONFIG_8260 */

#ifdef CONFIG_APUS
#define HARDWARE_MAPPED_SIZE (512*1024)
unsigned long __init apus_find_end_of_memory(void)
{
        int shadow = 0;

        /* The memory size reported by ADOS excludes the 512KB
           reserved for PPC exception registers and possibly 512KB
           containing a shadow of the ADOS ROM. */
        {
                unsigned long size = memory[0].size;

                /* If 2MB aligned, size was probably user
                   specified. We can't tell anything about shadowing
                   in this case so skip shadow assignment. */
                if (0 != (size & 0x1fffff)){
                        /* Align to 512KB to ensure correct handling
                           of both memfile and system specified
                           sizes. */
                        size = ((size+0x0007ffff) & 0xfff80000);
                        /* If memory is 1MB aligned, assume
                           shadowing. */
                        shadow = !(size & 0x80000);
                }

                /* Add the chunk that ADOS does not see. by aligning
                   the size to the nearest 2MB limit upwards.  */
                memory[0].size = ((size+0x001fffff) & 0xffe00000);
        }

        /* Now register the memory block. */
        mem_pieces_append(&phys_mem, memory[0].addr, memory[0].size);
        set_phys_avail(&phys_mem);

        /* Remove the memory chunks that are controlled by special
           Phase5 hardware. */
        {
                unsigned long top = memory[0].addr + memory[0].size;

                /* Remove the upper 512KB if it contains a shadow of
                   the ADOS ROM. FIXME: It might be possible to
                   disable this shadow HW. Check the booter
                   (ppc_boot.c) */
                if (shadow)
                {
                        top -= HARDWARE_MAPPED_SIZE;
                        mem_pieces_remove(&phys_avail, top,
                                          HARDWARE_MAPPED_SIZE, 0);
                }

                /* Remove the upper 512KB where the PPC exception
                   vectors are mapped. */
                top -= HARDWARE_MAPPED_SIZE;
#if 0
                /* This would be neat, but it breaks on A3000 machines!? */
                mem_pieces_remove(&phys_avail, top, 16384, 0);
#else
                mem_pieces_remove(&phys_avail, top, HARDWARE_MAPPED_SIZE, 0);
#endif

        }

        /* Linux/APUS only handles one block of memory -- the one on
           the PowerUP board. Other system memory is horrible slow in
           comparison. The user can use other memory for swapping
           using the z2ram device. */
        return memory[0].addr + memory[0].size;
}
#endif /* CONFIG_APUS */

/*
 * Initialize the hash table and patch the instructions in head.S.
 */
static void __init hash_init(void)
{
        int Hash_bits, mb, mb2;
        unsigned int hmask, ramsize, h;

        extern unsigned int hash_page_patch_A[], hash_page_patch_B[],
                hash_page_patch_C[], hash_page[];

        ramsize = (ulong)end_of_DRAM - KERNELBASE;
#ifdef CONFIG_PPC64BRIDGE
        /* The hash table has already been allocated and initialized
           in prom.c */
        Hash_mask = (Hash_size >> 7) - 1;
        hmask = Hash_mask >> 9;
        Hash_bits = __ilog2(Hash_size) - 7;
        mb = 25 - Hash_bits;
        if (Hash_bits > 16)
                Hash_bits = 16;
        mb2 = 25 - Hash_bits;

#else /* CONFIG_PPC64BRIDGE */

        if ( ppc_md.progress ) ppc_md.progress("hash:enter", 0x105);
        /*
         * Allow 64k of hash table for every 16MB of memory,
         * up to a maximum of 2MB.
         */
        for (h = 64<<10; h < ramsize / 256 && h < (2<<20); h *= 2)
                ;
        Hash_size = h;
        Hash_mask = (h >> 6) - 1;
        hmask = Hash_mask >> 10;
        Hash_bits = __ilog2(h) - 6;
        mb = 26 - Hash_bits;
        if (Hash_bits > 16)
                Hash_bits = 16;
        mb2 = 26 - Hash_bits;

        /* shrink the htab since we don't use it on 603's -- Cort */
        switch (_get_PVR()>>16) {
        case 3: /* 603 */
        case 6: /* 603e */
        case 7: /* 603ev */
        case 0x0081: /* 82xx */
                Hash_size = 0;
                Hash_mask = 0;
                break;
        default:
                /* on 601/4 let things be */
                break;
        }
        
        if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322);
        /* Find some memory for the hash table. */
        if ( Hash_size ) {
                Hash = mem_pieces_find(Hash_size, Hash_size);
                cacheable_memzero(Hash, Hash_size);
        } else
                Hash = 0;
#endif /* CONFIG_PPC64BRIDGE */

        printk("Total memory = %dMB; using %ldkB for hash table (at %p)\n",
               ramsize >> 20, Hash_size >> 10, Hash);
        if ( Hash_size )
        {
                if ( ppc_md.progress ) ppc_md.progress("hash:patch", 0x345);
                Hash_end = (PTE *) ((unsigned long)Hash + Hash_size);

                /*
                 * Patch up the instructions in head.S:hash_page
                 */
                hash_page_patch_A[0] = (hash_page_patch_A[0] & ~0xffff)
                        | (__pa(Hash) >> 16);
                hash_page_patch_A[1] = (hash_page_patch_A[1] & ~0x7c0)
                        | (mb << 6);
                hash_page_patch_A[2] = (hash_page_patch_A[2] & ~0x7c0)
                        | (mb2 << 6);
                hash_page_patch_B[0] = (hash_page_patch_B[0] & ~0xffff)
                        | hmask;
                hash_page_patch_C[0] = (hash_page_patch_C[0] & ~0xffff)
                        | hmask;
#if 0   /* see hash_page in head.S, note also patch_C ref below */
                hash_page_patch_D[0] = (hash_page_patch_D[0] & ~0xffff)
                        | hmask;
#endif
                /*
                 * Ensure that the locations we've patched have been written
                 * out from the data cache and invalidated in the instruction
                 * cache, on those machines with split caches.
                 */
                flush_icache_range((unsigned long) &hash_page_patch_A[0],
                                   (unsigned long) &hash_page_patch_C[1]);
        }
        else {
                Hash_end = 0;
                /*
                 * Put a blr (procedure return) instruction at the
                 * start of hash_page, since we can still get DSI
                 * exceptions on a 603.
                 */
                hash_page[0] = 0x4e800020;
                flush_icache_range((unsigned long) &hash_page[0],
                                   (unsigned long) &hash_page[1]);
        }
        if ( ppc_md.progress ) ppc_md.progress("hash:done", 0x205);
}
#elif defined(CONFIG_8xx)
/*
 * This is a big hack right now, but it may turn into something real
 * someday.
 *
 * For the 8xx boards (at this time anyway), there is nothing to initialize
 * associated the PROM.  Rather than include all of the prom.c
 * functions in the image just to get prom_init, all we really need right
 * now is the initialization of the physical memory region.
 */
unsigned long __init m8xx_find_end_of_memory(void)
{
        bd_t    *binfo;
        extern unsigned char __res[];
        
        binfo = (bd_t *)__res;

        phys_mem.regions[0].address = 0;
        phys_mem.regions[0].size = binfo->bi_memsize;   
        phys_mem.n_regions = 1;

        set_phys_avail(&phys_mem);
        return phys_mem.regions[0].address + phys_mem.regions[0].size;
}
#endif /* !CONFIG_4xx && !CONFIG_8xx */

#ifdef CONFIG_OAK
/*
 * Return the virtual address representing the top of physical RAM
 * on the Oak board.
 */
unsigned long __init
oak_find_end_of_memory(void)
{
        extern unsigned char __res[];

        unsigned long *ret;
        bd_t *bip = (bd_t *)__res;
        
        phys_mem.regions[0].address = 0;
        phys_mem.regions[0].size = bip->bi_memsize;
        phys_mem.n_regions = 1;

        set_phys_avail(&phys_mem);
        return (phys_mem.regions[0].address + phys_mem.regions[0].size);
}
#endif

/*
 * Set phys_avail to phys_mem less the kernel text/data/bss.
 */
void __init
set_phys_avail(struct mem_pieces *mp)
{
        unsigned long kstart, ksize;

        /*
         * Initially, available phyiscal memory is equivalent to all
         * physical memory.
         */

        phys_avail = *mp;

        /*
         * Map out the kernel text/data/bss from the available physical
         * memory.
         */

        kstart = __pa(_stext);  /* should be 0 */
        ksize = PAGE_ALIGN(klimit - _stext);

        mem_pieces_remove(&phys_avail, kstart, ksize, 0);
        mem_pieces_remove(&phys_avail, 0, 0x4000, 0);

#if defined(CONFIG_BLK_DEV_INITRD)
        /* Remove the init RAM disk from the available memory. */
        if (initrd_start) {
                mem_pieces_remove(&phys_avail, __pa(initrd_start),
                                  initrd_end - initrd_start, 1);
        }
#endif /* CONFIG_BLK_DEV_INITRD */
#ifdef CONFIG_ALL_PPC
        /* remove the RTAS pages from the available memory */
        if (rtas_data)
                mem_pieces_remove(&phys_avail, rtas_data, rtas_size, 1);
#endif /* CONFIG_ALL_PPC */
#ifdef CONFIG_PPC64BRIDGE
        /* Remove the hash table from the available memory */
        if (Hash)
                mem_pieces_remove(&phys_avail, __pa(Hash), Hash_size, 1);
#endif /* CONFIG_PPC64BRIDGE */
}