| | 1 | #include "vm_flags.h" |
| | 2 | #include <io.h> |
| | 3 | |
| | 4 | #define MAP_FLAGS (PTE_PRESENT | PTE_READ_WRITE) |
| | 5 | |
| | 6 | void * pt_setup(int smbase) { |
| | 7 | int i; |
| | 8 | outb(0x80, 0x51); |
| | 9 | |
| | 10 | /* The page directory and page table live at SMBASE and SMBASE + 0x1000, |
| | 11 | * respectively; clear them. */ |
| | 12 | int * pagedirectory = (int *) smbase; |
| | 13 | int * pagetable = (int *) (smbase + 0x1000); |
| | 14 | |
| | 15 | /* Clear out the page directory except for one entry pointing to the |
| | 16 | * page table, and clear the page table entirely. */ |
| | 17 | outb(0x80, 0x52); |
| | 18 | pagedirectory[0] = (smbase + 0x1000) | PTE_PRESENT | PTE_READ_WRITE; |
| | 19 | outb(0x80, 0x53); |
| | 20 | for (i = 1; i < 1024; i++) |
| | 21 | { |
| | 22 | pagedirectory[i] = 0; |
| | 23 | } |
| | 24 | |
| | 25 | outb(0x80, 0x54); |
| | 26 | for (i = 0; i < 1024; i++) |
| | 27 | { |
| | 28 | pagetable[i] = 0; |
| | 29 | } |
| | 30 | outb(0x80, 0x55); |
| | 31 | |
| | 32 | /* The page at 0x10000 - 0x10FFF points to the SMI entry point, |
| | 33 | * SMBASE + 0x8000. */ |
| | 34 | pagetable[16] = (0x8000 + smbase) | MAP_FLAGS; |
| | 35 | |
| | 36 | /* 0x11000 to 0x1EFFF map to the rest of ASEG up to SMBASE + 0xF000; |
| | 37 | * the page containing the saved state is not mappped to our code |
| | 38 | * region. */ |
| | 39 | |
| | 40 | for (i = 0; i < 8; i++) |
| | 41 | { |
| | 42 | pagetable[17 + i] = (i * 0x1000 + smbase) | MAP_FLAGS; |
| | 43 | } |
| | 44 | |
| | 45 | for (i = 0; i < 6; i++) |
| | 46 | { |
| | 47 | pagetable[25 + i] = (smbase + 0x9000 + i * 0x1000) | MAP_FLAGS; |
| | 48 | } |
| | 49 | |
| | 50 | outb(0x80, 0x56); |
| | 51 | /* Map 0xA8000 to itself. */ |
| | 52 | pagetable[0xA8] = 0xA8000 | MAP_FLAGS; |
| | 53 | pagetable[0xA9] = 0xA9000 | MAP_FLAGS; |
| | 54 | |
| | 55 | /* No TSEG yet. */ |
| | 56 | |
| | 57 | outb(0x80, 0x57); |
| | 58 | return pagedirectory; |
| | 59 | } |
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