Add variables to grub2 for Chrome OS bringup workarounds.

disk/efi/efidisk.c

 /*
  *  GRUB  --  GRand Unified Bootloader
  *  Copyright (C) 2006,2007,2008  Free Software Foundation, Inc.
  *
  *  GRUB is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation, either version 3 of the License, or
  *  (at your option) any later version.
  *
  *  GRUB is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <grub/disk.h>
 #include <grub/partition.h>
 #include <grub/mm.h>
 #include <grub/types.h>
 #include <grub/misc.h>
 #include <grub/err.h>
 #include <grub/term.h>
 #include <grub/efi/api.h>
 #include <grub/efi/efi.h>
 #include <grub/efi/disk.h>
+#include <grub/env.h>
 
 struct grub_efidisk_data
 {
   grub_efi_handle_t handle;
   grub_efi_device_path_t *device_path;
   grub_efi_device_path_t *last_device_path;
   grub_efi_block_io_t *block_io;
   grub_efi_disk_io_t *disk_io;
   struct grub_efidisk_data *next;
 };
@@ skipping 768 matching lines @@
 
       device_name = grub_malloc (grub_strlen (parent->name) + 1
                                  + grub_strlen (partition_name) + 1);
       if (! device_name)
         {
           grub_free (partition_name);
           grub_disk_close (parent);
           return 0;
         }
 
+      {
+        // This block is a temporary workaround used by Chrome OS. We set
+        // some variables that we can use in the grub.cfg file to ensure that
+        // we get the kernel and rootfs from the boot device, regardless of
+        // which device that is.
+        char *tmpbuf = grub_malloc (grub_strlen (parent->name) + 5);
+        if (! tmpbuf)
+        {
+          grub_free (device_name);
+          grub_free (partition_name);
+          grub_disk_close (parent);
+          return 0;
+        }
+
+        grub_sprintf (tmpbuf, "(%s,3)", parent->name);
+        grub_env_set ("grubpartA", tmpbuf);
+        grub_env_export ("grubpartA");
+        grub_sprintf (tmpbuf, "(%s,5)", parent->name);
+        grub_env_set ("grubpartB", tmpbuf);
+        grub_env_export ("grubpartB");
+        grub_free (tmpbuf);
+
+        // Translate hd0 to sda, hd1 to sdb, etc. parent->name is always
+        // either "fdN", "hdN", or "cdN". This trick won't work if N is > 9.
+        int index = parent->name[2] - '0';
+        // The Chrome OS BIOS doesn't enumerate the hard disk in recovery
+        // mode, so the first removable drive is hd0, not hd1. Linux always
+        // sees it though.
+        struct grub_efidisk_data *d = parent->data;
+        if (d->block_io->media->removable_media)
+          index++;
+
+        char devname[] = "sdXN";
+        devname[2] = 'a' + index;
+        devname[3] = '3';
+        grub_env_set ("linuxpartA", devname);
+        grub_env_export ("linuxpartA");
+        devname[3] = '5';
+        grub_env_set ("linuxpartB", devname);
+        grub_env_export ("linuxpartB");
+      }
+      
       grub_sprintf (device_name, "%s,%s", parent->name, partition_name);
       grub_free (partition_name);
       grub_disk_close (parent);
       return device_name;
     }
   else
     {
       /* This should be an entire disk.  */
       auto int find_disk (const char *name);
       char *device_name = 0;
@@ skipping 23 matching lines @@
           return 0;
 
         }
 
       grub_efidisk_iterate (find_disk);
       return device_name;
     }
 
   return 0;
 }