Make early physical page allocation truely reliable

Import upstream biosmem changes and adjust for local modifications.

Specifically, this change makes the biosmem module reliably track all
boot data by storing their addresses in a sorted array. This allows
both the early page allocator and the biosmem_free_usable function
to accurately find any range of free pages.

* i386/i386at/biosmem.c: Remove inclusion of <i386at/elf.h>.
(_start, _end): Remove variable declarations.
(BIOSMEM_MAX_BOOT_DATA): New macro.
(struct biosmem_boot_data): New type.
(biosmem_boot_data_array, biosmem_nr_boot_data): New variables.
(biosmem_heap_start, biosmem_heap_bottom, biosmem_heap_top,
biosmem_heap_end): Change type to phys_addr_t.
(biosmem_panic_inval_boot_data): New variable.
(biosmem_panic_too_many_boot_data): Likewise.
(biosmem_panic_toobig_msg): Variable renamed ...
(biosmem_panic_too_big_msg): ... to this.
(biosmem_register_boot_data): New function.
(biosmem_unregister_boot_data): Likewise.
(biosmem_map_adjust): Update reference to panic message.
(biosmem_map_find_avail): Add detailed description.
(biosmem_save_cmdline_sizes): Remove function.
(biosmem_find_heap_clip): Likewise.
(biosmem_find_heap): Likewise.
(biosmem_find_avail_clip, biosmem_find_avail): New functions.
(biosmem_setup_allocator): Receive const multiboot info, replace
calls to biosmem_find_heap with calls to biosmem_find_avail and
update accordingly. Register the heap as boot data.
(biosmem_xen_bootstrap): Register the Xen boot info and the heap as
boot data.
(biosmem_bootstrap): Receive const multiboot information. Remove call
to biosmem_save_cmdline_sizes.
(biosmem_bootalloc): Remove assertion on the VM system state.
(biosmem_type_desc, biosmem_map_show): Build only if DEBUG is true.
(biosmem_unregister_temporary_boot_data): New function.
(biosmem_free_usable_range): Change address range format.
(biosmem_free_usable_entry): Rewrite to use biosmem_find_avail
without abusing it.
(biosmem_free_usable): Call biosmem_unregister_temporary_boot_data,
update call to biosmem_free_usable_entry.
* i386/i386at/biosmem.h (biosmem_register_boot_data): New function.
(biosmem_bootalloc): Update description.
(biosmem_bootstrap): Update description and declaration.
(biosmem_free_usable): Likewise.
* i386/i386at/model_dep.c: Include <i386at/elf.h>.
(machine_init): Update call to biosmem_free_usable.
(register_boot_data): New function.
(i386at_init): Call register_boot_data where appropriate.

3 files changed, 316 insertions, 194 deletions

diff --git a/i386/i386at/biosmem.c b/i386/i386at/biosmem.c
index 567cc745..90ae54a9 100644
--- a/i386/i386at/biosmem.c
+++ b/i386/i386at/biosmem.c
@@ -18,7 +18,6 @@
 #include <string.h>
 #include <i386/model_dep.h>
 #include <i386at/biosmem.h>
-#include <i386at/elf.h>
 #include <kern/assert.h>
 #include <kern/debug.h>
 #include <kern/macros.h>
@@ -43,7 +42,26 @@
 #define BOOT_CGACHARS   (80 * 25)
 #define BOOT_CGACOLOR   0x7
 
-extern char _start, _end;
+#define BIOSMEM_MAX_BOOT_DATA 64
+
+/*
+ * Boot data descriptor.
+ *
+ * The start and end addresses must not be page-aligned, since there
+ * could be more than one range inside a single page.
+ */
+struct biosmem_boot_data {
+    phys_addr_t start;
+    phys_addr_t end;
+    boolean_t temporary;
+};
+
+/*
+ * Sorted array of boot data descriptors.
+ */
+static struct biosmem_boot_data biosmem_boot_data_array[BIOSMEM_MAX_BOOT_DATA]
+    __bootdata;
+static unsigned int biosmem_nr_boot_data __bootdata;
 
 /*
  * Maximum number of entries in the BIOS memory map.
@@ -73,14 +91,6 @@ struct biosmem_map_entry {
 };
 
 /*
- * Contiguous block of physical memory.
- */
-struct biosmem_segment {
-    phys_addr_t start;
-    phys_addr_t end;
-};
-
-/*
  * Memory map built from the information passed by the boot loader.
  *
  * If the boot loader didn't pass a valid memory map, a simple map is built
@@ -91,6 +101,14 @@ static struct biosmem_map_entry biosmem_map[BIOSMEM_MAX_MAP_SIZE * 2]
 static unsigned int biosmem_map_size __bootdata;
 
 /*
+ * Contiguous block of physical memory.
+ */
+struct biosmem_segment {
+    phys_addr_t start;
+    phys_addr_t end;
+};
+
+/*
  * Physical segment boundaries.
  */
 static struct biosmem_segment biosmem_segments[VM_PAGE_MAX_SEGS] __bootdata;
@@ -100,10 +118,10 @@ static struct biosmem_segment biosmem_segments[VM_PAGE_MAX_SEGS] __bootdata;
  *
  * This heap is located above BIOS memory.
  */
-static uint32_t biosmem_heap_start __bootdata;
-static uint32_t biosmem_heap_bottom __bootdata;
-static uint32_t biosmem_heap_top __bootdata;
-static uint32_t biosmem_heap_end __bootdata;
+static phys_addr_t biosmem_heap_start __bootdata;
+static phys_addr_t biosmem_heap_bottom __bootdata;
+static phys_addr_t biosmem_heap_top __bootdata;
+static phys_addr_t biosmem_heap_end __bootdata;
 
 /*
  * Boot allocation policy.
@@ -113,7 +131,11 @@ static uint32_t biosmem_heap_end __bootdata;
  */
 static boolean_t biosmem_heap_topdown __bootdata;
 
-static char biosmem_panic_toobig_msg[] __bootdata
+static char biosmem_panic_inval_boot_data[] __bootdata
+    = "biosmem: invalid boot data";
+static char biosmem_panic_too_many_boot_data[] __bootdata
+    = "biosmem: too many boot data ranges";
+static char biosmem_panic_too_big_msg[] __bootdata
     = "biosmem: too many memory map entries";
 #ifndef MACH_HYP
 static char biosmem_panic_setup_msg[] __bootdata
@@ -126,6 +148,103 @@ static char biosmem_panic_inval_msg[] __bootdata
 static char biosmem_panic_nomem_msg[] __bootdata
     = "biosmem: unable to allocate memory";
 
+void __boot
+biosmem_register_boot_data(phys_addr_t start, phys_addr_t end,
+                           boolean_t temporary)
+{
+    unsigned int i;
+
+    if (start >= end) {
+        boot_panic(biosmem_panic_inval_boot_data);
+    }
+
+    if (biosmem_nr_boot_data == ARRAY_SIZE(biosmem_boot_data_array)) {
+        boot_panic(biosmem_panic_too_many_boot_data);
+    }
+
+    for (i = 0; i < biosmem_nr_boot_data; i++) {
+        /* Check if the new range overlaps */
+        if ((end > biosmem_boot_data_array[i].start)
+             && (start < biosmem_boot_data_array[i].end)) {
+
+            /*
+             * If it does, check whether it's part of another range.
+             * For example, this applies to debugging symbols directly
+             * taken from the kernel image.
+             */
+            if ((start >= biosmem_boot_data_array[i].start)
+                && (end <= biosmem_boot_data_array[i].end)) {
+
+                /*
+                 * If it's completely included, make sure that a permanent
+                 * range remains permanent.
+                 *
+                 * XXX This means that if one big range is first registered
+                 * as temporary, and a smaller range inside of it is
+                 * registered as permanent, the bigger range becomes
+                 * permanent. It's not easy nor useful in practice to do
+                 * better than that.
+                 */
+                if (biosmem_boot_data_array[i].temporary != temporary) {
+                    biosmem_boot_data_array[i].temporary = FALSE;
+                }
+
+                return;
+            }
+
+            boot_panic(biosmem_panic_inval_boot_data);
+        }
+
+        if (end <= biosmem_boot_data_array[i].start) {
+            break;
+        }
+    }
+
+    boot_memmove(&biosmem_boot_data_array[i + 1],
+                 &biosmem_boot_data_array[i],
+                 (biosmem_nr_boot_data - i) * sizeof(*biosmem_boot_data_array));
+
+    biosmem_boot_data_array[i].start = start;
+    biosmem_boot_data_array[i].end = end;
+    biosmem_boot_data_array[i].temporary = temporary;
+    biosmem_nr_boot_data++;
+}
+
+static void __init
+biosmem_unregister_boot_data(phys_addr_t start, phys_addr_t end)
+{
+    unsigned int i;
+
+    if (start >= end) {
+        panic(biosmem_panic_inval_boot_data);
+    }
+
+    assert(biosmem_nr_boot_data != 0);
+
+    for (i = 0; biosmem_nr_boot_data; i++) {
+        if ((start == biosmem_boot_data_array[i].start)
+            && (end == biosmem_boot_data_array[i].end)) {
+            break;
+        }
+    }
+
+    if (i == biosmem_nr_boot_data) {
+        return;
+    }
+
+#if DEBUG
+    printf("biosmem: unregister boot data: %llx:%llx\n",
+           (unsigned long long)biosmem_boot_data_array[i].start,
+           (unsigned long long)biosmem_boot_data_array[i].end);
+#endif /* DEBUG */
+
+    biosmem_nr_boot_data--;
+
+    boot_memmove(&biosmem_boot_data_array[i],
+                 &biosmem_boot_data_array[i + 1],
+                 (biosmem_nr_boot_data - i) * sizeof(*biosmem_boot_data_array));
+}
+
 #ifndef MACH_HYP
 
 static void __boot
@@ -308,7 +427,7 @@ biosmem_map_adjust(void)
                  */
 
                 if (biosmem_map_size >= ARRAY_SIZE(biosmem_map))
-                    boot_panic(biosmem_panic_toobig_msg);
+                    boot_panic(biosmem_panic_too_big_msg);
 
                 biosmem_map[biosmem_map_size] = tmp;
                 biosmem_map_size++;
@@ -327,6 +446,16 @@ biosmem_map_adjust(void)
     biosmem_map_sort();
 }
 
+/*
+ * Find addresses of physical memory within a given range.
+ *
+ * This function considers the memory map with the [*phys_start, *phys_end]
+ * range on entry, and returns the lowest address of physical memory
+ * in *phys_start, and the highest address of unusable memory immediately
+ * following physical memory in *phys_end.
+ *
+ * These addresses are normally used to establish the range of a segment.
+ */
 static int __boot
 biosmem_map_find_avail(phys_addr_t *phys_start, phys_addr_t *phys_end)
 {
@@ -388,166 +517,86 @@ biosmem_segment_size(unsigned int seg_index)
     return biosmem_segments[seg_index].end - biosmem_segments[seg_index].start;
 }
 
-#ifndef MACH_HYP
-
-static void __boot
-biosmem_save_cmdline_sizes(struct multiboot_raw_info *mbi)
+static int __boot
+biosmem_find_avail_clip(phys_addr_t *avail_start, phys_addr_t *avail_end,
+                        phys_addr_t data_start, phys_addr_t data_end)
 {
-    struct multiboot_raw_module *mod;
-    uint32_t i, va;
+    phys_addr_t orig_end;
 
-    if (mbi->flags & MULTIBOOT_LOADER_CMDLINE) {
-        va = phystokv(mbi->cmdline);
-        mbi->unused0 = boot_strlen((char *)va) + 1;
-    }
-
-    if (mbi->flags & MULTIBOOT_LOADER_MODULES) {
-        unsigned long addr;
+    assert(data_start < data_end);
 
-        addr = phystokv(mbi->mods_addr);
+    orig_end = data_end;
+    data_start = vm_page_trunc(data_start);
+    data_end = vm_page_round(data_end);
 
-        for (i = 0; i < mbi->mods_count; i++) {
-            mod = (struct multiboot_raw_module *)addr + i;
-            va = phystokv(mod->string);
-            mod->reserved = boot_strlen((char *)va) + 1;
-        }
+    if (data_end < orig_end) {
+        boot_panic(biosmem_panic_inval_boot_data);
     }
-}
 
-static int __boot
-biosmem_find_heap_clip(phys_addr_t *heap_start, phys_addr_t *heap_end,
-                       phys_addr_t data_start, phys_addr_t data_end)
-{
-    assert(data_start < data_end);
-
-    if ((data_end <= *heap_start) || (data_start >= *heap_end)) {
+    if ((data_end <= *avail_start) || (data_start >= *avail_end)) {
         return 0;
     }
 
-    if (data_start > *heap_start) {
-        *heap_end = data_start;
+    if (data_start > *avail_start) {
+        *avail_end = data_start;
     } else {
-        if (data_end >= *heap_end) {
+        if (data_end >= *avail_end) {
             return -1;
         }
 
-        *heap_start = data_end;
+        *avail_start = data_end;
     }
 
     return 0;
 }
 
 /*
- * Find available memory for an allocation heap.
+ * Find available memory in the given range.
  *
  * The search starts at the given start address, up to the given end address.
- * If a range is found, it is stored through the heap_startp and heap_endp
+ * If a range is found, it is stored through the avail_startp and avail_endp
  * pointers.
  *
- * The search skips boot data, that is :
- *  - the kernel
- *  - the kernel command line
- *  - the module table
- *  - the modules
- *  - the modules command lines
- *  - the ELF section header table
- *  - the ELF .shstrtab, .symtab and .strtab sections
+ * The range boundaries are page-aligned on return.
  */
 static int __boot
-biosmem_find_heap(const struct multiboot_raw_info *mbi,
-                  phys_addr_t start, phys_addr_t end,
-                  phys_addr_t *heap_start, phys_addr_t *heap_end)
+biosmem_find_avail(phys_addr_t start, phys_addr_t end,
+                   phys_addr_t *avail_start, phys_addr_t *avail_end)
 {
-    struct multiboot_raw_module *mod;
-    struct elf_shdr *shdr;
-    unsigned long tmp;
+    phys_addr_t orig_start;
     unsigned int i;
     int error;
 
-    if (start >= end) {
-        return -1;
-    }
-
-    *heap_start = start;
-    *heap_end = end;
-
-    error = biosmem_find_heap_clip(heap_start, heap_end,
-                                   _kvtophys(&_start), _kvtophys(&_end));
-
-    if (error) {
-        return error;
-    }
+    assert(start <= end);
 
-    if ((mbi->flags & MULTIBOOT_LOADER_CMDLINE) && (mbi->cmdline != 0)) {
-        error = biosmem_find_heap_clip(heap_start, heap_end,
-                                       mbi->cmdline,
-                                       mbi->cmdline + mbi->unused0);
+    orig_start = start;
+    start = vm_page_round(start);
+    end = vm_page_trunc(end);
 
-        if (error) {
-            return error;
-        }
+    if ((start < orig_start) || (start >= end)) {
+        return -1;
     }
 
-    if (mbi->flags & MULTIBOOT_LOADER_MODULES) {
-        i = mbi->mods_count * sizeof(struct multiboot_raw_module);
-        error = biosmem_find_heap_clip(heap_start, heap_end,
-                                       mbi->mods_addr, mbi->mods_addr + i);
-
-        if (error) {
-            return error;
-        }
-
-        tmp = phystokv(mbi->mods_addr);
-
-        for (i = 0; i < mbi->mods_count; i++) {
-            mod = (struct multiboot_raw_module *)tmp + i;
-            error = biosmem_find_heap_clip(heap_start, heap_end,
-                                           mod->mod_start, mod->mod_end);
-
-            if (error) {
-                return error;
-            }
+    *avail_start = start;
+    *avail_end = end;
 
-            if (mod->string != 0) {
-                error = biosmem_find_heap_clip(heap_start, heap_end,
-                                               mod->string,
-                                               mod->string + mod->reserved);
-
-                if (error) {
-                    return error;
-                }
-            }
-        }
-    }
-
-    if (mbi->flags & MULTIBOOT_LOADER_SHDR) {
-        tmp = mbi->shdr_num * mbi->shdr_size;
-        error = biosmem_find_heap_clip(heap_start, heap_end,
-                                       mbi->shdr_addr, mbi->shdr_addr + tmp);
+    for (i = 0; i < biosmem_nr_boot_data; i++) {
+        error = biosmem_find_avail_clip(avail_start, avail_end,
+                                        biosmem_boot_data_array[i].start,
+                                        biosmem_boot_data_array[i].end);
 
         if (error) {
-            return error;
-        }
-
-        tmp = phystokv(mbi->shdr_addr);
-
-        for (i = 0; i < mbi->shdr_num; i++) {
-            shdr = (struct elf_shdr *)(tmp + (i * mbi->shdr_size));
-
-            if ((shdr->type != ELF_SHT_SYMTAB)
-                && (shdr->type != ELF_SHT_STRTAB))
-                continue;
-
-            error = biosmem_find_heap_clip(heap_start, heap_end,
-                                           shdr->addr, shdr->addr + shdr->size);
+            return -1;
         }
     }
 
     return 0;
 }
 
+#ifndef MACH_HYP
+
 static void __boot
-biosmem_setup_allocator(struct multiboot_raw_info *mbi)
+biosmem_setup_allocator(const struct multiboot_raw_info *mbi)
 {
     phys_addr_t heap_start, heap_end, max_heap_start, max_heap_end;
     phys_addr_t start, end;
@@ -569,7 +618,7 @@ biosmem_setup_allocator(struct multiboot_raw_info *mbi)
     start = BIOSMEM_END;
 
     for (;;) {
-        error = biosmem_find_heap(mbi, start, end, &heap_start, &heap_end);
+        error = biosmem_find_avail(start, end, &heap_start, &heap_end);
 
         if (error) {
             break;
@@ -586,17 +635,14 @@ biosmem_setup_allocator(struct multiboot_raw_info *mbi)
     if (max_heap_start >= max_heap_end)
         boot_panic(biosmem_panic_setup_msg);
 
-    max_heap_start = vm_page_round(max_heap_start);
-    max_heap_end = vm_page_trunc(max_heap_end);
-
-    if (max_heap_start >= max_heap_end)
-        boot_panic(biosmem_panic_setup_msg);
-
     biosmem_heap_start = max_heap_start;
     biosmem_heap_end = max_heap_end;
     biosmem_heap_bottom = biosmem_heap_start;
     biosmem_heap_top = biosmem_heap_end;
     biosmem_heap_topdown = TRUE;
+
+    /* Prevent biosmem_free_usable() from releasing the heap */
+    biosmem_register_boot_data(biosmem_heap_start, biosmem_heap_end, FALSE);
 }
 
 #endif /* MACH_HYP */
@@ -676,7 +722,6 @@ biosmem_xen_bootstrap(void)
     biosmem_heap_end = boot_info.nr_pages << PAGE_SHIFT;
 
 #ifndef __LP64__
-    /* TODO Check that this actually makes sense */
     if (biosmem_heap_end > VM_PAGE_DIRECTMAP_LIMIT)
         biosmem_heap_end = VM_PAGE_DIRECTMAP_LIMIT;
 #endif /* __LP64__ */
@@ -693,12 +738,18 @@ biosmem_xen_bootstrap(void)
      * first.
      */
     biosmem_heap_topdown = FALSE;
+
+    /*
+     * Prevent biosmem_free_usable() from releasing the Xen boot information
+     * and the heap.
+     */
+    biosmem_register_boot_data(0, biosmem_heap_end, FALSE);
 }
 
 #else /* MACH_HYP */
 
 void __boot
-biosmem_bootstrap(struct multiboot_raw_info *mbi)
+biosmem_bootstrap(const struct multiboot_raw_info *mbi)
 {
     if (mbi->flags & MULTIBOOT_LOADER_MMAP)
         biosmem_map_build(mbi);
@@ -706,12 +757,6 @@ biosmem_bootstrap(struct multiboot_raw_info *mbi)
         biosmem_map_build_simple(mbi);
 
     biosmem_bootstrap_common();
-
-    /*
-     * The kernel and modules command lines will be memory mapped later
-     * during initialization. Their respective sizes must be saved.
-     */
-    biosmem_save_cmdline_sizes(mbi);
     biosmem_setup_allocator(mbi);
 }
 
@@ -722,8 +767,6 @@ biosmem_bootalloc(unsigned int nr_pages)
 {
     unsigned long addr, size;
 
-    assert(!vm_page_ready());
-
     size = vm_page_ptoa(nr_pages);
 
     if (size == 0)
@@ -764,6 +807,8 @@ biosmem_directmap_end(void)
         return biosmem_segment_end(VM_PAGE_SEG_DMA);
 }
 
+#if DEBUG
+
 static const char * __init
 biosmem_type_desc(unsigned int type)
 {
@@ -797,9 +842,15 @@ biosmem_map_show(void)
                entry->base_addr + entry->length,
                biosmem_type_desc(entry->type));
 
-    printf("biosmem: heap: %x-%x\n", biosmem_heap_start, biosmem_heap_end);
+    printf("biosmem: heap: %llx:%llx\n",
+           (unsigned long long)biosmem_heap_start,
+           (unsigned long long)biosmem_heap_end);
 }
 
+#else /* DEBUG */
+#define biosmem_map_show()
+#endif /* DEBUG */
+
 static void __init
 biosmem_load_segment(struct biosmem_segment *seg, uint64_t max_phys_end)
 {
@@ -865,24 +916,31 @@ biosmem_setup(void)
     }
 }
 
-#ifndef MACH_HYP
-
 static void __init
-biosmem_free_usable_range(phys_addr_t start, phys_addr_t end)
+biosmem_unregister_temporary_boot_data(void)
 {
-    struct vm_page *page;
+    struct biosmem_boot_data *data;
+    unsigned int i;
 
-    assert(start < end);
+    for (i = 0; i < biosmem_nr_boot_data; i++) {
+        data = &biosmem_boot_data_array[i];
 
-    start = vm_page_round(start);
-    end = vm_page_round(end);
+        if (!data->temporary) {
+            continue;
+        }
 
-    if (start >= end) {
-        return;
+        biosmem_unregister_boot_data(data->start, data->end);
+        i = (unsigned int)-1;
     }
+}
+
+static void __init
+biosmem_free_usable_range(phys_addr_t start, phys_addr_t end)
+{
+    struct vm_page *page;
 
 #if DEBUG
-    printf("biosmem: release to vm_page: %llx-%llx (%lluk)\n",
+    printf("biosmem: release to vm_page: %llx:%llx (%lluk)\n",
            (unsigned long long)start, (unsigned long long)end,
            (unsigned long long)((end - start) >> 10));
 #endif
@@ -896,40 +954,32 @@ biosmem_free_usable_range(phys_addr_t start, phys_addr_t end)
 }
 
 static void __init
-biosmem_free_usable_entry(struct multiboot_raw_info *mbi, phys_addr_t start,
-                          phys_addr_t end)
+biosmem_free_usable_entry(phys_addr_t start, phys_addr_t end)
 {
-    phys_addr_t heap_start, heap_end;
+    phys_addr_t avail_start, avail_end;
     int error;
 
-    /* XXX Abuse biosmem_find_heap to locate usable areas */
-
     for (;;) {
-        error = biosmem_find_heap(mbi, start, end, &heap_start, &heap_end);
-
-        if (error) {
-            break;
-        }
-
-        error = biosmem_find_heap_clip(&heap_start, &heap_end,
-                                       biosmem_heap_start, biosmem_heap_end);
+        error = biosmem_find_avail(start, end, &avail_start, &avail_end);
 
         if (error) {
             break;
         }
 
-        biosmem_free_usable_range(heap_start, heap_end);
-        start = heap_end;
+        biosmem_free_usable_range(avail_start, avail_end);
+        start = avail_end;
     }
 }
 
 void __init
-biosmem_free_usable(struct multiboot_raw_info *mbi)
+biosmem_free_usable(void)
 {
     struct biosmem_map_entry *entry;
     uint64_t start, end;
     unsigned int i;
 
+    biosmem_unregister_temporary_boot_data();
+
     for (i = 0; i < biosmem_map_size; i++) {
         entry = &biosmem_map[i];
 
@@ -955,8 +1005,6 @@ biosmem_free_usable(struct multiboot_raw_info *mbi)
             continue;
         }
 
-        biosmem_free_usable_entry(mbi, start, end);
+        biosmem_free_usable_entry(start, end);
     }
 }
-
-#endif /* MACH_HYP */
diff --git a/i386/i386at/biosmem.h b/i386/i386at/biosmem.h
index f48cfc30..7824c168 100644
--- a/i386/i386at/biosmem.h
+++ b/i386/i386at/biosmem.h
@@ -40,25 +40,39 @@
 #define BIOSMEM_END         0x100000
 
 /*
- * Early initialization of the biosmem module.
+ * Report reserved addresses to the biosmem module.
  *
- * This function processes the given multiboot data for BIOS-provided
- * memory information, and sets up a bootstrap physical page allocator.
+ * Once all boot data have been registered, the user can set up the
+ * early page allocator.
  *
- * It is called before paging is enabled.
+ * If the range is marked temporary, it will be unregistered when
+ * biosmem_free_usable() is called, so that pages that used to store
+ * these boot data may be released to the VM system.
+ */
+void biosmem_register_boot_data(phys_addr_t start, phys_addr_t end,
+                                boolean_t temporary);
+
+/*
+ * Initialize the early page allocator.
+ *
+ * This function uses the memory map provided by the boot loader along
+ * with the registered boot data addresses to set up a heap of free pages
+ * of physical memory.
+ *
+ * Note that on Xen, this function registers all the Xen boot information
+ * as boot data itself.
  */
 #ifdef MACH_HYP
 void biosmem_xen_bootstrap(void);
 #else /* MACH_HYP */
-void biosmem_bootstrap(struct multiboot_raw_info *mbi);
+void biosmem_bootstrap(const struct multiboot_raw_info *mbi);
 #endif /* MACH_HYP */
 
 /*
  * Allocate contiguous physical pages during bootstrap.
  *
- * This function is called before paging is enabled. The pages returned
- * are guaranteed to be part of the direct physical mapping when paging
- * is enabled.
+ * The pages returned are guaranteed to be part of the direct physical
+ * mapping when paging is enabled.
  *
  * This function should only be used to allocate initial page table pages.
  * Those pages are later loaded into the VM system (as reserved pages)
@@ -80,9 +94,10 @@ void biosmem_setup(void);
 
 /*
  * Free all usable memory.
+ *
+ * This function releases all pages that aren't used by boot data and have
+ * not already been loaded into the VM system.
  */
-#ifndef MACH_HYP
-void biosmem_free_usable(struct multiboot_raw_info *mbi);
-#endif /* MACH_HYP */
+void biosmem_free_usable(void);
 
 #endif /* _X86_BIOSMEM_H */
diff --git a/i386/i386at/model_dep.c b/i386/i386at/model_dep.c
index 8e98bd9e..87d6cefa 100644
--- a/i386/i386at/model_dep.c
+++ b/i386/i386at/model_dep.c
@@ -66,6 +66,7 @@
 #include <i386/model_dep.h>
 #include <i386at/autoconf.h>
 #include <i386at/biosmem.h>
+#include <i386at/elf.h>
 #include <i386at/idt.h>
 #include <i386at/int_init.h>
 #include <i386at/kd.h>
@@ -158,9 +159,7 @@ void machine_init(void)
 	 * This is particularly important for the Linux drivers which
 	 * require available DMA memory.
 	 */
-#ifndef MACH_HYP
-	biosmem_free_usable((struct multiboot_raw_info *) &boot_info);
-#endif /* MACH_HYP */
+	biosmem_free_usable();
 
 	/*
 	 * Set up to use floating point.
@@ -274,6 +273,65 @@ void db_reset_cpu(void)
 	halt_all_cpus(1);
 }
 
+#ifndef	MACH_HYP
+
+static void
+register_boot_data(const struct multiboot_raw_info *mbi)
+{
+	struct multiboot_raw_module *mod;
+	struct elf_shdr *shdr;
+	unsigned long tmp;
+	unsigned int i;
+
+	extern char _start[], _end[];
+
+	/* XXX For now, register all boot data as permanent */
+
+	biosmem_register_boot_data(_kvtophys(&_start), _kvtophys(&_end), FALSE);
+
+	if ((mbi->flags & MULTIBOOT_LOADER_CMDLINE) && (mbi->cmdline != 0)) {
+		biosmem_register_boot_data(mbi->cmdline,
+					   mbi->cmdline + strlen((void *)mbi->cmdline) + 1, FALSE);
+	}
+
+	if (mbi->flags & MULTIBOOT_LOADER_MODULES) {
+		i = mbi->mods_count * sizeof(struct multiboot_raw_module);
+		biosmem_register_boot_data(mbi->mods_addr, mbi->mods_addr + i, FALSE);
+
+		tmp = phystokv(mbi->mods_addr);
+
+		for (i = 0; i < mbi->mods_count; i++) {
+			mod = (struct multiboot_raw_module *)tmp + i;
+			biosmem_register_boot_data(mod->mod_start, mod->mod_end, FALSE);
+
+			if (mod->string != 0) {
+				biosmem_register_boot_data(mod->string,
+							   mod->string + strlen((void *)mod->string) + 1,
+							   FALSE);
+			}
+		}
+	}
+
+	if (mbi->flags & MULTIBOOT_LOADER_SHDR) {
+		tmp = mbi->shdr_num * mbi->shdr_size;
+		biosmem_register_boot_data(mbi->shdr_addr, mbi->shdr_addr + tmp, FALSE);
+
+		tmp = phystokv(mbi->shdr_addr);
+
+		for (i = 0; i < mbi->shdr_num; i++) {
+			shdr = (struct elf_shdr *)(tmp + (i * mbi->shdr_size));
+
+			if ((shdr->type != ELF_SHT_SYMTAB)
+			    && (shdr->type != ELF_SHT_STRTAB))
+				continue;
+
+			biosmem_register_boot_data(shdr->addr, shdr->addr + shdr->size, FALSE);
+		}
+	}
+}
+
+#endif /* MACH_HYP */
+
 /*
  * Basic PC VM initialization.
  * Turns on paging and changes the kernel segments to use high linear addresses.
@@ -301,6 +359,7 @@ i386at_init(void)
 #ifdef MACH_HYP
 	biosmem_xen_bootstrap();
 #else /* MACH_HYP */
+	register_boot_data((struct multiboot_raw_info *) &boot_info);
 	biosmem_bootstrap((struct multiboot_raw_info *) &boot_info);
 #endif /* MACH_HYP */