add paging fork of aseg; totally not working yet.

[netwatch.git] / aseg-paging / pagetable.c

diff --git a/aseg-paging/pagetable.c b/aseg-paging/pagetable.c
new file mode 100644 (file)
index 0000000..83a1e54
--- /dev/null
+++ b/aseg-paging/pagetable.c
@@ -0,0 +1,59 @@
+#include "vm_flags.h"
+#include <io.h>
+
+#define MAP_FLAGS      (PTE_PRESENT | PTE_READ_WRITE)
+
+void * pt_setup(int smbase) {
+       int i;
+       outb(0x80, 0x51);
+
+       /* The page directory and page table live at SMBASE and SMBASE + 0x1000,
+        * respectively; clear them. */
+       int * pagedirectory = (int *) smbase;
+       int * pagetable = (int *) (smbase + 0x1000);
+
+       /* Clear out the page directory except for one entry pointing to the
+        * page table, and clear the page table entirely. */
+       outb(0x80, 0x52);
+       pagedirectory[0] = (smbase + 0x1000) | PTE_PRESENT | PTE_READ_WRITE;
+       outb(0x80, 0x53);
+       for (i = 1; i < 1024; i++)
+       {
+               pagedirectory[i] = 0;
+       }
+
+       outb(0x80, 0x54);
+       for (i = 0; i < 1024; i++)
+       {
+               pagetable[i] = 0;
+       }
+       outb(0x80, 0x55);
+
+       /* The page at 0x10000 - 0x10FFF points to the SMI entry point,
+        * SMBASE + 0x8000. */
+       pagetable[16] = (0x8000 + smbase) | MAP_FLAGS;
+
+       /* 0x11000 to 0x1EFFF map to the rest of ASEG up to SMBASE + 0xF000;
+        * the page containing the saved state is not mappped to our code
+        * region.  */
+
+       for (i = 0; i < 8; i++)
+       {
+               pagetable[17 + i] = (i * 0x1000 + smbase) | MAP_FLAGS;
+       }
+
+       for (i = 0; i < 6; i++)
+       {
+               pagetable[25 + i] = (smbase + 0x9000 + i * 0x1000) | MAP_FLAGS;
+       }
+
+       outb(0x80, 0x56);
+       /* Map 0xA8000 to itself. */
+       pagetable[0xA8] = 0xA8000 | MAP_FLAGS;
+       pagetable[0xA9] = 0xA9000 | MAP_FLAGS;
+
+       /* No TSEG yet. */
+
+       outb(0x80, 0x57);
+       return pagedirectory;
+}