Dev-mode allows booting self-signed kernels by default.

When you enter dev-mode,

  Pressing Ctrl-U to boot from USB is DISABLED.
  Booting any self-signed kernel from the SSD is ENABLED.

This replaces the "crossystem dev_boot_custom" argument with
"crossystem dev_boot_signed_only", which has the opposite polarity.
So if you want to dev-mode to only boot official kernels, you have to
explictly set it that way. If you leave dev-mode and then come back,
it will go back to the conditions shown above.

BUG=chrome-os-partner:5954
TEST=manual

Just run the factory flow. It was broken; this should fix it (except for any
workarounds that were added while it was broken; those may need to be
reverted).

Change-Id: I13e0edbc0e77c5d6ea609dabf771085006cd1805
Reviewed-on: https://gerrit.chromium.org/gerrit/11853
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
diff --git a/host/lib/crossystem.c b/host/lib/crossystem.c
index 5bd4c62..5c2adde 100644
--- a/host/lib/crossystem.c
+++ b/host/lib/crossystem.c
@@ -390,8 +390,8 @@
     value = VbGetNvStorage(VBNV_LOCALIZATION_INDEX);
   } else if (!strcasecmp(name,"dev_boot_usb")) {
     value = VbGetNvStorage(VBNV_DEV_BOOT_USB);
-  } else if (!strcasecmp(name,"dev_boot_custom")) {
-    value = VbGetNvStorage(VBNV_DEV_BOOT_CUSTOM);
+  } else if (!strcasecmp(name,"dev_boot_signed_only")) {
+    value = VbGetNvStorage(VBNV_DEV_BOOT_SIGNED_ONLY);
   }
   /* Other parameters */
   else if (!strcasecmp(name,"cros_debug")) {
@@ -471,8 +471,8 @@
     return VbSetNvStorage(VBNV_LOCALIZATION_INDEX, value);
   } else if (!strcasecmp(name,"dev_boot_usb")) {
     return VbSetNvStorage(VBNV_DEV_BOOT_USB, value);
-  } else if (!strcasecmp(name,"dev_boot_custom")) {
-    return VbSetNvStorage(VBNV_DEV_BOOT_CUSTOM, value);
+  } else if (!strcasecmp(name,"dev_boot_signed_only")) {
+    return VbSetNvStorage(VBNV_DEV_BOOT_SIGNED_ONLY, value);
   }
 
   return -1;