Paging test: identity map first 16MiB

kernel/src/main.rs

@@ -9,6 +9,7 @@ mod interrupts;
 mod shell;
 mod syscalls;
 mod task;
+mod paging;
 
 use core::arch::asm;
 use core::panic::PanicInfo;
@@ -18,6 +19,8 @@ use filesystem::fat::FAT;
 use interrupts::idt::IDT;
 use shell::SHELL;
 use syscalls::print::PRINTER;
+use paging::PAGING;
+use paging::PageTable;
 
 use libfelix;
 
@@ -42,6 +45,26 @@ pub extern "C" fn _start() -> ! {
         asm!("mov esp, {}", in(reg) STACK_START);
     }
 
+    //setup paging
+    unsafe {
+        let table0 = PageTable::new(0x0);
+        let table1 = PageTable::new(0x0040_0000);
+        let table2 = PageTable::new(0x0080_0000);
+        let table3 = PageTable::new(0x00C0_0000);
+        //let table2 = PageTable::test();
+        PAGING.set_table(0, &table0);
+        PAGING.set_table(1, &table1);
+        PAGING.set_table(2, &table2);
+        PAGING.set_table(3, &table3);
+        //PAGING.set_table(15, &table2);
+
+        PAGING.enable();
+    }
+
+    unsafe {
+        asm!("xchg bx, bx");
+    }
+
     unsafe {
         //init idt
         IDT.init();
@@ -96,9 +119,9 @@ pub extern "C" fn _start() -> ! {
     }
 
     //bochs magic breakpoint
-    /*unsafe {
+    unsafe {
         asm!("xchg bx, bx");
-    }*/
+    }
 
     //enable hardware interrupts
     unsafe {

kernel/src/paging.rs

@@ -34,23 +34,22 @@ pub struct PageTable {
 }
 
 impl PageTable {
-    pub fn new() -> Self {
+    pub fn new(from: u32) -> Self {
         let mut table = Self { entries: [0; 1024] };
 
         for i in 0..1024 {
             //0b011 (supervisor, write, present)
-            table.entries[i] = ((i * 0x1000) | 0b011) as u32;
+            table.entries[i] = (((i * 0x1000) + from as usize) | 0b011) as u32;
         }
 
         table
     }
 
     pub fn test() -> Self {
         let mut table = Self { entries: [0; 1024] };
-
-        for i in 0..1024 {
+        for i in 0..4 {
             //0b011 (supervisor, write, present)
-            table.entries[i] = (((1024 + i) * 0x1000) | 0b011) as u32;
+            table.entries[i] = (((i * 0x1000) + 0x0050_0000) | 0b011) as u32;
         }
 
         table