i86pc/dboot/dboot_startkern.c

	dboot_startkern.c revision ae115bc77f6fcde83175c75b4206dc2e50747966
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/types.h>
#include <sys/machparam.h>
#include <sys/x86_archext.h>
#include <sys/systm.h>
#include <sys/mach_mmu.h>

#include <sys/multiboot.h>

extern multiboot_header_t mb_header;
extern int have_cpuid(void);
extern uint32_t get_cpuid_edx(uint32_t *eax);

#include <sys/inttypes.h>
#include <sys/bootinfo.h>
#include <sys/mach_mmu.h>
#include <sys/boot_console.h>

#include "dboot_printf.h"
#include "dboot_xboot.h"
#include "dboot_elfload.h"

/*
 * This file contains code that runs to transition us from either a multiboot
 * compliant loader (32 bit non-paging) or Xen domain loader to regular kernel
 * execution. Its task is to setup the kernel memory image and page tables.
 *
 * The code executes as:
 *  - 32 bits under GRUB (for 32 or 64 bit Solaris)
 *  - 32 bit program for Xen 32 bit
 *  - 64 bit program for Xen 64 bit (at least that's my assumption for now)
 *
 * Under Xen, we must create mappings for any memory beyond the initial
 * start of day allocation (such as the kernel itself).
 *
 * When not under Xen, the mapping between maddr_t and paddr_t is 1:1.
 * Since we are running in real mode, so all such memory is accessible.
 */

/*
 * Standard bits used in PTE (page level) and PTP (internal levels)
 */
x86pte_t ptp_bits = PT_VALID | PT_REF | PT_USER | PT_WRITABLE | PT_USER;
x86pte_t pte_bits = PT_VALID | PT_REF | PT_MOD | PT_NOCONSIST | PT_WRITABLE;

/*
 * This is the target addresses (physical) where the kernel text and data
 * nucleus pages will be unpacked. On Xen this is actually a virtual address.
 */
paddr_t ktext_phys;
uint32_t ksize = 2 * FOUR_MEG;  /* kernel nucleus is 8Meg */

static uint64_t target_kernel_text; /* value to use for KERNEL_TEXT */

/*
 * The stack is setup in assembler before entering startup_kernel()
 */
char stack_space[STACK_SIZE];

/*
 * Used to track physical memory allocation
 */
static paddr_t next_avail_addr = 0;

multiboot_info_t *mb_info;

/*
 * This contains information passed to the kernel
 */
struct xboot_info boot_info[2]; /* extra space to fix alignement for amd64 */
struct xboot_info *bi;

/*
 * Page table and memory stuff.
 */
static uint64_t max_mem;            /* maximum memory address */

/*
 * Information about processor MMU
 */
int amd64_support = 0;
int largepage_support = 0;
int pae_support = 0;
int pge_support = 0;
int NX_support = 0;

/*
 * Low 32 bits of kernel entry address passed back to assembler.
 * When running a 64 bit kernel, the high 32 bits are 0xffffffff.
 */
uint32_t entry_addr_low;

/*
 * Memlists for the kernel. We shouldn't need a lot of these.
 */
#define MAX_MEMLIST (10)
struct boot_memlist memlists[MAX_MEMLIST];
uint_t memlists_used = 0;

#define MAX_MODULES (10)
struct boot_modules modules[MAX_MODULES];
uint_t modules_used = 0;

/*
 * Debugging macros
 */
uint_t prom_debug = 0;
uint_t map_debug = 0;

/*
 * The Xen/Grub specific code builds the initial memlists. This code does
 * sort/merge/link for final use.
 */
static void
sort_physinstall(void)
{
    int i;
    int j;
    struct boot_memlist tmp;

    /*
     * Now sort the memlists, in case they weren't in order.
     * Yeah, this is a bubble sort; small, simple and easy to get right.
     */
    DBG_MSG("Sorting phys-installed list\n");
    for (j = memlists_used - 1; j > 0; --j) {
        for (i = 0; i < j; ++i) {
            if (memlists[i].addr < memlists[i + 1].addr)
                continue;
            tmp = memlists[i];
            memlists[i] = memlists[i + 1];
            memlists[i + 1] = tmp;
        }
    }

    /*
     * Merge any memlists that don't have holes between them.
     */
    for (i = 0; i <= memlists_used - 1; ++i) {
        if (memlists[i].addr + memlists[i].size != memlists[i + 1].addr)
            continue;

        if (prom_debug)
            dboot_printf(
                "merging mem segs %" PRIx64 "...%" PRIx64
                " w/ %" PRIx64 "...%" PRIx64 "\n",
                memlists[i].addr,
                memlists[i].addr + memlists[i].size,
                memlists[i + 1].addr,
                memlists[i + 1].addr + memlists[i + 1].size);

        memlists[i].size += memlists[i + 1].size;
        for (j = i + 1; j < memlists_used - 1; ++j)
            memlists[j] = memlists[j + 1];
        --memlists_used;
        DBG(memlists_used);
        --i;    /* after merging we need to reexamine, so do this */
    }

    if (prom_debug) {
        dboot_printf("\nFinal memlists:\n");
        for (i = 0; i < memlists_used; ++i) {
            dboot_printf("\t%d: addr=%" PRIx64 " size=%"
                PRIx64 "\n", i, memlists[i].addr, memlists[i].size);
        }
    }

    /*
     * link together the memlists with native size pointers
     */
    memlists[0].next = 0;
    memlists[0].prev = 0;
    for (i = 1; i < memlists_used; ++i) {
        memlists[i].prev = (native_ptr_t)(uintptr_t)(memlists + i - 1);
        memlists[i].next = 0;
        memlists[i - 1].next = (native_ptr_t)(uintptr_t)(memlists + i);
    }
    bi->bi_phys_install = (native_ptr_t)memlists;
    DBG(bi->bi_phys_install);
}

x86pte_t
get_pteval(paddr_t table, uint_t index)
{
    if (pae_support)
        return (((x86pte_t *)(uintptr_t)table)[index]);
    return (((x86pte32_t *)(uintptr_t)table)[index]);
}

/*ARGSUSED*/
void
set_pteval(paddr_t table, uint_t index, uint_t level, x86pte_t pteval)
{
    uintptr_t tab_addr = (uintptr_t)table;

    if (pae_support)
        ((x86pte_t *)tab_addr)[index] = pteval;
    else
        ((x86pte32_t *)tab_addr)[index] = (x86pte32_t)pteval;
    if (level == top_level && level == 2)
        reload_cr3();
}

paddr_t
make_ptable(x86pte_t *pteval, uint_t level)
{
    paddr_t new_table = (paddr_t)(uintptr_t)mem_alloc(MMU_PAGESIZE);

    if (level == top_level && level == 2)
        *pteval = pa_to_ma((uintptr_t)new_table) | PT_VALID;
    else
        *pteval = pa_to_ma((uintptr_t)new_table) | ptp_bits;

    if (map_debug)
        dboot_printf("new page table lvl=%d paddr=0x%lx ptp=0x%"
            PRIx64 "\n", level, (ulong_t)new_table, *pteval);
    return (new_table);
}

x86pte_t *
map_pte(paddr_t table, uint_t index)
{
    return ((x86pte_t *)(uintptr_t)(table + index * pte_size));
}

#if 0   /* useful if debugging */
/*
 * dump out the contents of page tables...
 */
static void
dump_tables(void)
{
    uint_t save_index[4];   /* for recursion */
    char *save_table[4];    /* for recursion */
    uint_t  l;
    uint64_t va;
    uint64_t pgsize;
    int index;
    int i;
    x86pte_t pteval;
    char *table;
    static char *tablist = "\t\t\t";
    char *tabs = tablist + 3 - top_level;
    uint_t pa, pa1;

    dboot_printf("Finished pagetables:\n");
    table = (char *)top_page_table;
    l = top_level;
    va = 0;
    for (index = 0; index < ptes_per_table; ++index) {
        pgsize = 1ull << shift_amt[l];
        if (pae_support)
            pteval = ((x86pte_t *)table)[index];
        else
            pteval = ((x86pte32_t *)table)[index];
        if (pteval == 0)
            goto next_entry;

        dboot_printf("%s %lx[0x%x] = %" PRIx64 ", va=%" PRIx64,
            tabs + l, table, index, (uint64_t)pteval, va);
        pa = ma_to_pa(pteval & MMU_PAGEMASK);
        dboot_printf(" physaddr=%" PRIx64 "\n", pa);

        /*
         * Don't try to walk hypervisor private pagetables
         */
        if ((l > 1 || (l == 1 && (pteval & PT_PAGESIZE) == 0))) {
            save_table[l] = table;
            save_index[l] = index;
            --l;
            index = -1;
            table = (char *)(uintptr_t)
                ma_to_pa(pteval & MMU_PAGEMASK);
            goto recursion;
        }

        /*
         * shorten dump for consecutive mappings
         */
        for (i = 1; index + i < ptes_per_table; ++i) {
            if (pae_support)
                pteval = ((x86pte_t *)table)[index + i];
            else
                pteval = ((x86pte32_t *)table)[index + i];
            if (pteval == 0)
                break;
            pa1 = ma_to_pa(pteval & MMU_PAGEMASK);
            if (pa1 != pa + i * pgsize)
                break;
        }
        if (i > 2) {
            dboot_printf("%s...\n", tabs + l);
            va += pgsize * (i - 2);
            index += i - 2;
        }
next_entry:
        va += pgsize;
        if (l == 3 && index == 256) /* VA hole */
            va = 0xffff800000000000ull;
recursion:
        ;
    }
    if (l < top_level) {
        ++l;
        index = save_index[l];
        table = save_table[l];
        goto recursion;
    }
}
#endif

/*
 * Add a mapping for the physical page at the given virtual address.
 */
static void
map_pa_at_va(paddr_t pa, native_ptr_t va, uint_t level)
{
    x86pte_t *ptep;
    x86pte_t pteval;

    pteval = pa_to_ma(pa) | pte_bits;
    if (level > 0)
        pteval |= PT_PAGESIZE;
    if (va >= target_kernel_text && pge_support)
        pteval |= PT_GLOBAL;

    if (map_debug && pa != va)
        dboot_printf("mapping pa=0x%" PRIx64 " va=0x%" PRIx64
            " pte=0x%" PRIx64 " l=%d\n",
            (uint64_t)pa, (uint64_t)va, pteval, level);

    /*
     * Find the pte that will map this address. This creates any
     * missing intermediate level page tables
     */
    ptep = find_pte(va, NULL, level, 0);

    /*
     * On Xen we must use hypervisor calls to modify the PTE, since
     * paging is active. On real hardware we just write to the pagetables
     * which aren't in use yet.
     */
    if (va < 1024 * 1024)
        pteval |= PT_NOCACHE;       /* for video RAM */
    if (pae_support)
        *ptep = pteval;
    else
        *((x86pte32_t *)ptep) = (x86pte32_t)pteval;
}

/*
 * During memory allocation, find the highest address not used yet.
 */
static void
check_higher(paddr_t a)
{
    if (a < next_avail_addr)
        return;
    next_avail_addr = RNDUP(a + 1, MMU_PAGESIZE);
    DBG(next_avail_addr);
}

/*
 * Walk through the module information finding the last used address.
 * The first available address will become the top level page table.
 *
 * We then build the phys_install memlist from the multiboot information.
 */
static void
init_mem_alloc(void)
{
    mb_memory_map_t *mmap;
    mb_module_t *mod;
    uint64_t start;
    uint64_t end;
    uint64_t page_offset = MMU_PAGEOFFSET;  /* needs to be 64 bits */
    extern char _end[];
    int i;

    DBG_MSG("Entered init_mem_alloc()\n");
    DBG((uintptr_t)mb_info);

    /*
     * search the modules to find the last used address
     * we'll build the module list while we're walking through here
     */
    DBG_MSG("\nFinding Modules\n");
    check_higher((paddr_t)&_end);
    for (mod = (mb_module_t *)(mb_info->mods_addr), i = 0;
        i < mb_info->mods_count;
        ++mod, ++i) {
        if (prom_debug) {
            dboot_printf("\tmodule #%d: %s at: 0x%lx, len 0x%lx\n",
                i, (char *)(mod->mod_name),
                (ulong_t)mod->mod_start, (ulong_t)mod->mod_end);
        }
        modules[i].bm_addr = mod->mod_start;
        modules[i].bm_size = mod->mod_end;

        check_higher(mod->mod_end);
    }
    bi->bi_modules = (native_ptr_t)modules;
    DBG(bi->bi_modules);
    bi->bi_module_cnt = mb_info->mods_count;
    DBG(bi->bi_module_cnt);

    /*
     * Walk through the memory map from multiboot and build our memlist
     * structures. Note these will have native format pointers.
     */
    DBG_MSG("\nFinding Memory Map\n");
    DBG(mb_info->flags);
    max_mem = 0;
    if (mb_info->flags & 0x40) {
        DBG(mb_info->mmap_addr);
        DBG(mb_info->mmap_length);
        check_higher(mb_info->mmap_addr + mb_info->mmap_length);

        for (mmap = (mb_memory_map_t *)mb_info->mmap_addr;
            (uint32_t)mmap < mb_info->mmap_addr + mb_info->mmap_length;
            mmap = (mb_memory_map_t *)((uint32_t)mmap + mmap->size
            + sizeof (mmap->size))) {

            start = ((uint64_t)mmap->base_addr_high << 32) +
                mmap->base_addr_low;
            end = start + ((uint64_t)mmap->length_high << 32) +
                mmap->length_low;

            if (prom_debug) {
                dboot_printf("\ttype: %d %" PRIx64 "..%"
                    PRIx64 "\n", mmap->type, start, end);
            }

            /*
             * only type 1 is usable RAM
             */
            if (mmap->type != 1)
                continue;

            /*
             * page align start and end
             */
            start = (start + page_offset) & ~page_offset;
            end &= ~page_offset;
            if (end <= start)
                continue;

            if (end > max_mem)
                max_mem = end;

            memlists[memlists_used].addr = start;
            memlists[memlists_used].size = end - start;
            ++memlists_used;    /* no overflow check */
        }
    } else if (mb_info->flags & 0x01) {
        DBG(mb_info->mem_lower);
        memlists[memlists_used].addr = 0;
        memlists[memlists_used].size = mb_info->mem_lower * 1024;
        ++memlists_used;
        DBG(mb_info->mem_upper);
        memlists[memlists_used].addr = 1024 * 1024;
        memlists[memlists_used].size = mb_info->mem_upper * 1024;
        ++memlists_used;
    } else {
        dboot_panic("No memory info from boot loader!!!\n");
    }

    check_higher(bi->bi_cmdline);

    /*
     * finish processing the physinstall list
     */
    sort_physinstall();
}

/*
 * Simple memory allocator, allocates aligned physical memory.
 * Note that startup_kernel() only allocates memory, never frees.
 * Memory usage just grows in an upward direction.
 */
static void *
do_mem_alloc(uint32_t size, uint32_t align)
{
    uint_t i;
    uint64_t best;
    uint64_t start;
    uint64_t end;

    /*
     * make sure size is a multiple of pagesize
     */
    size = RNDUP(size, MMU_PAGESIZE);
    next_avail_addr = RNDUP(next_avail_addr, align);

    /*
     * a really large bootarchive that causes you to run out of memory
     * may cause this to blow up
     */
    /* LINTED E_UNEXPECTED_UINT_PROMOTION */
    best = (uint64_t)-size;
    for (i = 0; i < memlists_used; ++i) {
        start = memlists[i].addr;
        end = start + memlists[i].size;

        /*
         * did we find the desired address?
         */
        if (start <= next_avail_addr && next_avail_addr + size <= end) {
            best = next_avail_addr;
            goto done;
        }

        /*
         * if not is this address the best so far?
         */
        if (start > next_avail_addr && start < best &&
            RNDUP(start, align) + size <= end)
            best = RNDUP(start, align);
    }

    /*
     * We didn't find exactly the address we wanted, due to going off the
     * end of a memory region. Return the best found memory address.
     */
done:
    next_avail_addr = best + size;
    (void) memset((void *)(uintptr_t)best, 0, size);
    return ((void *)(uintptr_t)best);
}

void *
mem_alloc(uint32_t size)
{
    return (do_mem_alloc(size, MMU_PAGESIZE));
}


/*
 * Build page tables to map all of memory used so far as well as the kernel.
 */
static void
build_page_tables(void)
{
    uint32_t psize;
    uint32_t level;
    uint32_t off;
    uint32_t i;
    uint64_t start;
    uint64_t end;
    uint64_t next_mapping;

    /*
     * If we're not using Xen, we need to create the top level pagetable.
     */
    top_page_table = (paddr_t)(uintptr_t)mem_alloc(MMU_PAGESIZE);
    DBG((uintptr_t)top_page_table);

    /*
     * Determine if we'll use large mappings for kernel, then map it.
     */
    if (largepage_support) {
        psize = lpagesize;
        level = 1;
    } else {
        psize = MMU_PAGESIZE;
        level = 0;
    }

    DBG_MSG("Mapping kernel\n");
    DBG(ktext_phys);
    DBG(target_kernel_text);
    DBG(ksize);
    DBG(psize);
    for (off = 0; off < ksize; off += psize)
        map_pa_at_va(ktext_phys + off, target_kernel_text + off, level);

    /*
     * The kernel will need a 1 page window to work with page tables
     */
    bi->bi_pt_window = (uintptr_t)mem_alloc(MMU_PAGESIZE);
    DBG(bi->bi_pt_window);
    bi->bi_pte_to_pt_window =
        (uintptr_t)find_pte(bi->bi_pt_window, NULL, 0, 0);
    DBG(bi->bi_pte_to_pt_window);

    /*
     * Under multiboot we need 1:1 mappings for all of low memory, which
     * includes our pagetables. The following code works because our
     * simple memory allocator only grows usage in an upwards direction.
     *
     * We map *all* possible addresses below 1 Meg, since things like
     * the video RAM are down there.
     *
     * Skip memory between 1M and _start, this acts as a reserve
     * of memory usable for DMA.
     */
    next_mapping = (uintptr_t)_start & MMU_PAGEMASK;
    if (map_debug)
        dboot_printf("1:1 map pa=0..1Meg\n");
    for (start = 0; start < 1024 * 1024; start += MMU_PAGESIZE)
        map_pa_at_va(start, start, 0);

    for (i = 0; i < memlists_used; ++i) {
        start = memlists[i].addr;
        if (start < next_mapping)
            start = next_mapping;

        end = start + memlists[i].size;

        if (map_debug)
            dboot_printf("1:1 map pa=%" PRIx64 "..%" PRIx64 "\n",
                start, end);
        while (start < end && start < next_avail_addr) {
            map_pa_at_va(start, start, 0);
            start += MMU_PAGESIZE;
        }
    }

    DBG_MSG("\nPage tables constructed\n");
}

#define NO_MULTIBOOT    \
"multiboot is no longer used to boot the Solaris Operating System.\n\
The grub entry should be changed to:\n\
kernel$ /platform/i86pc/kernel/$ISADIR/unix\n\
module$ /platform/i86pc/$ISADIR/boot_archive\n\
See http://www.sun.com/msg/SUNOS-8000-AK for details.\n"

/*
 * startup_kernel has a pretty simple job. It builds pagetables which reflect
 * 1:1 mappings for all memory in use. It then also adds mappings for
 * the kernel nucleus at virtual address of target_kernel_text using large page
 * mappings. The page table pages are also accessible at 1:1 mapped
 * virtual addresses.
 */
/*ARGSUSED*/
void
startup_kernel(void)
{
    char *cmdline;
    uintptr_t addr;

    /*
     * At this point we are executing in a 32 bit real mode.
     */
    cmdline = (char *)mb_info->cmdline;
    prom_debug = (strstr(cmdline, "prom_debug") != NULL);
    map_debug = (strstr(cmdline, "map_debug") != NULL);
    bcons_init(cmdline);
    DBG_MSG("\n\nSolaris prekernel set: ");
    DBG_MSG(cmdline);
    DBG_MSG("\n");

    if (strstr(cmdline, "multiboot") != NULL) {
        dboot_panic(NO_MULTIBOOT);
    }

    /*
     * boot info must be 16 byte aligned for 64 bit kernel ABI
     */
    addr = (uintptr_t)boot_info;
    addr = (addr + 0xf) & ~0xf;
    bi = (struct xboot_info *)addr;
    DBG((uintptr_t)bi);
    bi->bi_cmdline = (native_ptr_t)(uintptr_t)cmdline;

    /*
     * Need correct target_kernel_text value
     */
#if defined(_BOOT_TARGET_amd64)
    target_kernel_text = KERNEL_TEXT_amd64;
#else
    target_kernel_text = KERNEL_TEXT_i386;
#endif
    DBG(target_kernel_text);

    /*
     * use cpuid to enable MMU features
     */
    if (have_cpuid()) {
        uint32_t eax, edx;

        eax = 1;
        edx = get_cpuid_edx(&eax);
        if (edx & CPUID_INTC_EDX_PSE)
            largepage_support = 1;
        if (edx & CPUID_INTC_EDX_PGE)
            pge_support = 1;
        if (edx & CPUID_INTC_EDX_PAE)
            pae_support = 1;

        eax = 0x80000000;
        edx = get_cpuid_edx(&eax);
        if (eax >= 0x80000001) {
            eax = 0x80000001;
            edx = get_cpuid_edx(&eax);
            if (edx & CPUID_AMD_EDX_LM)
                amd64_support = 1;
            if (edx & CPUID_AMD_EDX_NX)
                NX_support = 1;
        }
    } else {
        dboot_printf("cpuid not supported\n");
    }

#if defined(_BOOT_TARGET_amd64)
    if (amd64_support == 0)
        dboot_panic("long mode not supported, rebooting\n");
    else if (pae_support == 0)
        dboot_panic("long mode, but no PAE; rebooting\n");
#endif

    /*
     * initialize our memory allocator
     */
    init_mem_alloc();

    /*
     * configure mmu information
     */
#if !defined(_BOOT_TARGET_amd64)
    if (pae_support && (max_mem > FOUR_GIG || NX_support)) {
#endif
        shift_amt = shift_amt_pae;
        ptes_per_table = 512;
        pte_size = 8;
        lpagesize = TWO_MEG;
#if defined(_BOOT_TARGET_amd64)
        top_level = 3;
#else
        top_level = 2;
#endif
#if !defined(_BOOT_TARGET_amd64)
    } else {
        pae_support = 0;
        NX_support = 0;
        shift_amt = shift_amt_nopae;
        ptes_per_table = 1024;
        pte_size = 4;
        lpagesize = FOUR_MEG;
        top_level = 1;
    }
#endif

    DBG(pge_support);
    DBG(NX_support);
    DBG(largepage_support);
    DBG(amd64_support);
    DBG(top_level);
    DBG(pte_size);
    DBG(ptes_per_table);
    DBG(lpagesize);

    ktext_phys = FOUR_MEG;      /* from UNIX Mapfile */

#if defined(_BOOT_TARGET_amd64)
    /*
     * For grub, copy kernel bits from the ELF64 file to final place.
     */
    DBG_MSG("\nAllocating nucleus pages.\n");
    ktext_phys = (uintptr_t)do_mem_alloc(ksize, FOUR_MEG);
    if (ktext_phys == 0)
        dboot_panic("failed to allocate aligned kernel memory\n");
    if (dboot_elfload64(mb_header.load_addr) != 0)
        dboot_panic("failed to parse kernel ELF image, rebooting\n");

#endif
    DBG(ktext_phys);

    /*
     * Allocate page tables.
     */
    build_page_tables();

    /*
     * return to assembly code to switch to running kernel
     */
    entry_addr_low = (uint32_t)target_kernel_text;
    DBG(entry_addr_low);
    bi->bi_use_largepage = largepage_support;
    bi->bi_use_pae = pae_support;
    bi->bi_use_pge = pge_support;
    bi->bi_use_nx = NX_support;
    bi->bi_next_paddr = next_avail_addr;
    DBG(bi->bi_next_paddr);
    bi->bi_next_vaddr = (uintptr_t)next_avail_addr;
    DBG(bi->bi_next_vaddr);
    bi->bi_mb_info = (uintptr_t)mb_info;
    bi->bi_top_page_table = (uintptr_t)top_page_table;

    bi->bi_kseg_size = FOUR_MEG;
    DBG(bi->bi_kseg_size);

#if 0       /* useful if debugging initial page tables */
    if (prom_debug)
        dump_tables();
#endif

    DBG_MSG("\n\n*** DBOOT DONE -- back to asm to jump to kernel\n\n");
}