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37
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1 #include "kernel.h"
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2
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3 multiboot_info_t *multiboot_info = 0; // Set by startup code.
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4 uint64_t available_memory = 0;
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5 uint64_t ramdisk_location = 0;
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6
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7 /* Retrieve memory information from multiboot header */
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8 void read_multiboot_info()
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9 {
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10 if ((multiboot_info->flags & (1 << 6)) == (1 << 6))
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11 {
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12 multiboot_memory_map_t *mmap;
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13 for (mmap = (multiboot_memory_map_t*)(uint64_t)multiboot_info->mmap_addr;
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14 (uint64_t)mmap < multiboot_info->mmap_addr + multiboot_info->mmap_length;
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15 mmap = (multiboot_memory_map_t*) ( (uint64_t)mmap + mmap->size + sizeof(mmap->size)) )
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16 {
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17 /*
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18 printf("size: %d, start: 0x%x, length=0x%x, type=%d\n", mmap->size,
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19 mmap->base, mmap->length, mmap->type);
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20 */
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21
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22 if ( (mmap->type == 1) && (mmap->base == 0x100000) )
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23 {
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24 available_memory = mmap->length;
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25 }
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26 }
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27 }
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28
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29 if (available_memory == 0)
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30 {
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31 panic("Found no usable memory in grub's memory map\n");
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32 }
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33
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34 if ((multiboot_info->flags & (1 << 3)) == (1 << 3))
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35 {
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36 uint64_t i;
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37 multiboot_module_t *mod = (multiboot_module_t*)(uint64_t)multiboot_info->mods_addr;
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38 for (i=0; i<multiboot_info->mods_count; i++)
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39 {
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40 // TODO: determine better way of finding the initrd module.
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41 if (i == 0)
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42 {
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43 ramdisk_location = mod->mod_start;
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44 }
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45
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46 // Make sure that placement malloc does not overwrite the ramdisk.
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47 uint64_t new_placement = (uint64_t)mod->mod_end;
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48 if (new_placement > placement_address)
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49 {
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50 if ((new_placement & 0xFFF) != 0)
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51 {
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52 new_placement = (new_placement & (~0xFFF)) + 0x1000; // Align to 4 KiB page.
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53 }
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54 placement_address = new_placement;
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55 }
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56 mod++; // Go to next module.
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57 }
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58 }
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59 }
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60
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