kern/main.c

   1 /* main.c - the kernel main routine */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2002,2003,2005,2006,2008  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/kernel.h>
  21 #include <grub/misc.h>
  22 #include <grub/symbol.h>
  23 #include <grub/dl.h>
  24 #include <grub/term.h>
  25 #include <grub/rescue.h>
  26 #include <grub/file.h>
  27 #include <grub/device.h>
  28 #include <grub/env.h>
  29 #include <grub/mm.h>
  30
  31 void
  32 grub_module_iterate (int (*hook) (struct grub_module_header *header))
  33 {
  34   struct grub_module_info *modinfo;
  35   struct grub_module_header *header;
  36   grub_addr_t modbase;
  37
  38   modbase = grub_arch_modules_addr ();
  39   modinfo = (struct grub_module_info *) modbase;
  40
  41   /* Check if there are any modules.  */
  42   if ((modinfo == 0) || modinfo->magic != GRUB_MODULE_MAGIC)
  43     return;
  44
  45   for (header = (struct grub_module_header *) (modbase + modinfo->offset);
  46        header < (struct grub_module_header *) (modbase + modinfo->size);
  47        header = (struct grub_module_header *) ((char *) header + header->size))
  48     {
  49       if (hook (header))
  50         break;
  51     }
  52 }
  53
  54 /* Load all modules in core.  */
  55 static void
  56 grub_load_modules (void)
  57 {
  58   auto int hook (struct grub_module_header *);
  59   int hook (struct grub_module_header *header)
  60     {
  61       /* Not an ELF module, skip.  */
  62       if (header->type != OBJ_TYPE_ELF)
  63         return 0;
  64
  65       if (! grub_dl_load_core ((char *) header + sizeof (struct grub_module_header),
  66                                (header->size - sizeof (struct grub_module_header))))
  67         grub_fatal ("%s", grub_errmsg);
  68
  69       return 0;
  70     }
  71
  72   grub_module_iterate (hook);
  73 }
  74
  75 /* Write hook for the environment variables of root. Remove surrounding
  76    parentheses, if any.  */
  77 static char *
  78 grub_env_write_root (struct grub_env_var *var __attribute__ ((unused)),
  79                      const char *val)
  80 {
  81   /* XXX Is it better to check the existence of the device?  */
  82   grub_size_t len = grub_strlen (val);
  83
  84   if (val[0] == '(' && val[len - 1] == ')')
  85     return grub_strndup (val + 1, len - 2);
  86
  87   return grub_strdup (val);
  88 }
  89
  90 /* Set the root device according to the dl prefix.  */
  91 static void
  92 grub_set_root_dev (void)
  93 {
  94   const char *prefix;
  95
  96   grub_register_variable_hook ("root", 0, grub_env_write_root);
  97   grub_env_export ("root");
  98
  99   prefix = grub_env_get ("prefix");
 100
 101   if (prefix)
 102     {
 103       char *dev;
 104
 105       dev = grub_file_get_device_name (prefix);
 106       if (dev)
 107         {
 108           grub_env_set ("root", dev);
 109           grub_free (dev);
 110         }
 111     }
 112 }
 113
 114 /* Load the normal mode module and execute the normal mode if possible.  */
 115 static void
 116 grub_load_normal_mode (void)
 117 {
 118   /* Load the module.  */
 119   grub_dl_load ("normal");
 120
 121   /* Something went wrong.  Print errors here to let user know why we're entering rescue mode.  */
 122   grub_print_error ();
 123 }
 124
 125 /* The main routine.  */
 126 void
 127 grub_main (void)
 128 {
 129   /* First of all, initialize the machine.  */
 130   grub_machine_init ();
 131
 132   /* Hello.  */
 133   grub_setcolorstate (GRUB_TERM_COLOR_HIGHLIGHT);
 134   grub_printf ("Welcome to GRUB!\n\n");
 135   grub_setcolorstate (GRUB_TERM_COLOR_STANDARD);
 136
 137   /* Load pre-loaded modules and free the space.  */
 138   grub_register_exported_symbols ();
 139   grub_load_modules ();
 140
 141   /* It is better to set the root device as soon as possible,
 142      for convenience.  */
 143   grub_machine_set_prefix ();
 144   grub_env_export ("prefix");
 145   grub_set_root_dev ();
 146
 147   /* Load the normal mode module.  */
 148   grub_load_normal_mode ();
 149
 150   /* Enter the rescue mode.  */
 151   grub_enter_rescue_mode ();
 152 }