--- a/cos/kernel/Makefile	Mon Jan 16 20:47:05 2012 +0100
+++ b/cos/kernel/Makefile	Mon Jan 16 21:38:55 2012 +0100
@@ -8,7 +8,8 @@
 	-fno-builtin -mcmodel=large -Wall -Wextra -Werror
 
 OBJECTS = video.o snprintf.o kernel.o asmcode.o handlers.o keyboard.o \
-			klib.o malloc.o task.o mm.o timer.o fs.o initrd.o
+			klib.o malloc.o task.o mm.o timer.o fs.o initrd.o multiboot.o \
+			shell.o
 
 lcfos.bin: $(CRT0) $(OBJECTS) kernel.ld
 	ld -g -T kernel.ld -s --cref -Map=kernel.map -o lcfos.bin $(CRT0) $(OBJECTS)

--- a/cos/kernel/kernel.c	Mon Jan 16 20:47:05 2012 +0100
+++ b/cos/kernel/kernel.c	Mon Jan 16 21:38:55 2012 +0100
@@ -1,21 +1,5 @@
 #include "kernel.h"
 
-static void testMalloc()
-{
-   char *a, *b;
-
-   printf("Testing malloc\n");
-   a = kmalloc(100);
-   printf("Got a at %x\n", a);
-   a[0] = 'A';
-   b = kmalloc(22);
-   printf("Got b at %x\n", b);
-   b[0] = 'B';
-   kfree(a);
-}
-
-multiboot_info_t *multiboot_info = 0; // Set by startup code.
-
 /* This routine initializes the kernel.
  * We are left here in 64-bit long mode with the first 6 MB identity mapped.
  * */
@@ -24,60 +8,18 @@
    // No kmalloc required here yet:
    init_screen();
    setupIDT();
-
-   /* Retrieve memory information from multiboot header */
-   uint64_t available_memory = 0;
-   if ((multiboot_info->flags & (1 << 6)) == (1 << 6))
-   {
-      multiboot_memory_map_t *mmap;
-      for (mmap = (multiboot_memory_map_t*)(uint64_t)multiboot_info->mmap_addr; 
-            (uint64_t)mmap < multiboot_info->mmap_addr + multiboot_info->mmap_length; 
-            mmap = (multiboot_memory_map_t*) ( (uint64_t)mmap + mmap->size + sizeof(mmap->size)) )
-      {
-         /*
-         printf("size: %d, start: 0x%x, length=0x%x, type=%d\n", mmap->size, 
-            mmap->base, mmap->length, mmap->type);
-         */
-
-         if ( (mmap->type == 1) && (mmap->base == 0x100000) )
-         {
-            available_memory = mmap->length;
-         }
-      }
-   }
-   
-   if (available_memory == 0)
-   {
-      panic("Found no usable memory in grub's memory map\n");
-   }
-
-   printf("Running with %d MB ram\n", available_memory / 1000000);
-
-   init_memory(available_memory); // Setup paging and memory manager
-
+   read_multiboot_info(); // Parse the GRUB multiboot header.
+   init_memory(available_memory); // Setup a new paging scheme and memory manager
+   // From here kmalloc can be used.
    keyboard_init();
    timer_init();
+   printf("Ramdisk location: %p\n", ramdisk_location);
 
    /*
    fs_node_t *fs_root = 0;
-   if ( (multiboot_info->flags & (1<<3)) == (1<<3))
-   {
-      printf("Mod count: %d\n", multiboot_info->mods_count);
-      uint64_t i;
-      multiboot_module_t *mod;
-      for (i=0, mod=(multiboot_module_t*)(uint64_t)multiboot_info->mods_addr; i<multiboot_info->mods_count; i++, mod++)
-      {
-         printf("Mod start: %x, end: %x\n", mod->mod_start, mod->mod_end);
-         if (i == 0)
-         {
-            uint64_t ramdisk_location = ((uint32_t*)((uint64_t)multiboot_info->mods_addr))[0];
-            fs_root = initialize_initrd(ramdisk_location);
-         }
-         // TODO: Make sure that placement malloc does not overwrite the ramdisk.
-         printf("Mod size: %d", mod->mod_end - mod->mod_start);
-      }
-   }
    
+   fs_root = initialize_initrd(ramdisk_location);
+
    if (fs_root != 0)
    {
       fs_dirent_t *node = 0;
@@ -89,49 +31,7 @@
    }
    */
 
-
-   // TODO: make below a user space program!
-   printf("Welcome!\n");
-
-  while (1) 
-  {
-    char buffer[70];
-    printf(">");
-    getline(buffer, 70);
-    // TODO: interpret this line with python :)
-    printf("\n");
-    if (buffer[0] == 'x') 
-    {
-      printf("System time in ms: %d\n", getTimeMS());
-    }
-    if (buffer[0] == 't')
-    {
-        testMalloc();
-    }
-    if ( strncmp(buffer, "help", 4)) 
-    {
-      printf("Help\n Try one of these commands:\n");
-      printf(" x: print system time in ms\n");
-      printf(" r: reboot\n");
-      printf(" t: test\n");
-      printf(" b: break\n");
-    }
-    if (strncmp(buffer, "r", 1))
-    {
-       reboot();
-    }
-    if (strncmp(buffer, "b", 1))
-    {
-       magicBochsBreak();
-    }
-      if (strncmp(buffer, "pf", 2))
-      {
-      /* Test general protection exception */
-      uint64_t *x;
-      x = (uint64_t*)0x4000000; // Address that is not mapped
-      *x = 0x2; // trigger paging exception
-      }
-   }
+   // TODO: make shell a user space program!
+   shell(); // Start user shell
 }
 
-

--- a/cos/kernel/kernel.h	Mon Jan 16 20:47:05 2012 +0100
+++ b/cos/kernel/kernel.h	Mon Jan 16 21:38:55 2012 +0100
@@ -329,5 +329,13 @@
 uint64_t getTimeMS();
 void timer_init(void);
 
+// Multiboot:
+extern uint64_t available_memory;
+extern uint64_t ramdisk_location;
+void read_multiboot_info(void);
+
+// Shell
+void shell(void);
+
 #endif
 

--- a/cos/kernel/mm.c	Mon Jan 16 20:47:05 2012 +0100
+++ b/cos/kernel/mm.c	Mon Jan 16 21:38:55 2012 +0100
@@ -6,6 +6,7 @@
 
 #include "kernel.h"
 
+// Bitmap that keeps track of all the 4 kB memory pages in the system:
 static uint64_t *frames = 0;
 static uint64_t nframes = 0;
 
@@ -55,13 +56,17 @@
    return (uint64_t) -1;
 }
 
-// Memory manager functions:
+/*
+ * Initializes the memory manager, allocating a bitmap once.
+ */
 void init_memory(uint64_t total_mem_size)
 {
+   printf("Running with %d MB ram\n", total_mem_size / 1000000);
+
    // Only here placement malloc is used!
    //
-   // Allocate and clear bits to remember which 4kb-frames are in use:
-   nframes = (total_mem_size / 0x1000);
+   // Allocate and clear bits to remember which 4KiB-frames are in use:
+   nframes = (total_mem_size / 0x1000); // Calculate number of frames
    frames = (uint64_t*)kmalloc_int( (nframes / 64) * sizeof(uint64_t) );
    memset(frames, 0, (nframes / 64) * sizeof(uint64_t));
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cos/kernel/multiboot.c	Mon Jan 16 21:38:55 2012 +0100
@@ -0,0 +1,60 @@
+#include "kernel.h"
+
+multiboot_info_t *multiboot_info = 0; // Set by startup code.
+uint64_t available_memory = 0;
+uint64_t ramdisk_location = 0;
+
+/* Retrieve memory information from multiboot header */
+void read_multiboot_info()
+{
+   if ((multiboot_info->flags & (1 << 6)) == (1 << 6))
+   {
+      multiboot_memory_map_t *mmap;
+      for (mmap = (multiboot_memory_map_t*)(uint64_t)multiboot_info->mmap_addr; 
+            (uint64_t)mmap < multiboot_info->mmap_addr + multiboot_info->mmap_length; 
+            mmap = (multiboot_memory_map_t*) ( (uint64_t)mmap + mmap->size + sizeof(mmap->size)) )
+      {
+         /*
+         printf("size: %d, start: 0x%x, length=0x%x, type=%d\n", mmap->size, 
+            mmap->base, mmap->length, mmap->type);
+         */
+
+         if ( (mmap->type == 1) && (mmap->base == 0x100000) )
+         {
+            available_memory = mmap->length;
+         }
+      }
+   }
+
+   if (available_memory == 0)
+   {
+      panic("Found no usable memory in grub's memory map\n");
+   }
+
+   if ((multiboot_info->flags & (1 << 3)) == (1 << 3))
+   {
+      uint64_t i;
+      multiboot_module_t *mod = (multiboot_module_t*)(uint64_t)multiboot_info->mods_addr;
+      for (i=0; i<multiboot_info->mods_count; i++)
+      {
+         // TODO: determine better way of finding the initrd module.
+         if (i == 0)
+         {
+            ramdisk_location = mod->mod_start;
+         }
+
+         // Make sure that placement malloc does not overwrite the ramdisk.
+         uint64_t new_placement = (uint64_t)mod->mod_end;
+         if (new_placement > placement_address)
+         {
+            if ((new_placement & 0xFFF) != 0)
+            {
+               new_placement = (new_placement & (~0xFFF)) + 0x1000; // Align to 4 KiB page.
+            }
+            placement_address = new_placement;
+         }
+         mod++; // Go to next module.
+      }
+   }
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cos/kernel/shell.c	Mon Jan 16 21:38:55 2012 +0100
@@ -0,0 +1,66 @@
+#include "kernel.h"
+
+/* Interactive shell, should be eventually a user space
+  program */
+
+static void testMalloc()
+{
+   char *a, *b;
+
+   printf("Testing malloc\n");
+   a = kmalloc(100);
+   printf("Got a at %x\n", a);
+   a[0] = 'A';
+   b = kmalloc(22);
+   printf("Got b at %x\n", b);
+   b[0] = 'B';
+   kfree(a);
+}
+
+void shell()
+{
+   printf("Welcome!\n");
+   while (1) 
+   {
+      char buffer[70];
+      printf(">");
+      getline(buffer, 70);
+      // TODO: interpret this line with python :)
+      printf("\n");
+      if (buffer[0] == 'x') 
+      {
+         printf("System time in ms: %d\n", getTimeMS());
+      }
+    if (buffer[0] == 't')
+    {
+        testMalloc();
+    }
+    if ( strncmp(buffer, "help", 4)) 
+    {
+      printf("Help\n Try one of these commands:\n");
+      printf(" x: print system time in ms\n");
+      printf(" r: reboot\n");
+      printf(" t: test\n");
+      printf(" b: break\n");
+    }
+
+      if (strncmp(buffer, "r", 1))
+      {
+         reboot();
+      }
+
+      if (strncmp(buffer, "b", 1))
+      {
+         magicBochsBreak();
+      }
+
+      if (strncmp(buffer, "pf", 2))
+      {
+         /* Test general protection exception */
+         uint64_t *x;
+         x = (uint64_t*)0x4000000; // Address that is not mapped
+         *x = 0x2; // trigger paging exception
+      }
+   }
+}
+