`"prefix" is not set` error message in early GRUB startup

[Seth Goldberg]

Hi,

  Recently, I've been seeing the error message in the subject line while GRUB2 
is starting.  I've tracked it down to code in normal.mod (specifically, the 
code in GRUB_MOD_INIT(normal) that tries to grub_dl_load the gzio module. 
Since normal.mod is loaded by the call to grub_load_modules() in main() and 
that call is BEFORE the call to grub_machine_set_prefix(), the prefix is not 
used to find gzio (another interesting thing to note is that even if gzio is 
embedded in the core image, if it is present AFTER normal.mod, the loader does 
not realize this and tries to load it from the prefix directory -- that should 
probably be fixed also).  Another interesting thing to note is that normal's 
init function, by virtue of calling grub_context_init(), calls grub_env_export 
for both prefix and root (which has the side effect of setting them to the 
empty string if they don't exist at the time).  This can also cause subtle 
problems if other modules access root or prefix during the course of 
grub_load_modules().

 My suggested fix is to move the calls to grub_machine_set_prefix() and 
grub_set_root_dev before grub_load_modules().  A cursory examination of these 
functions doesn't reveal any dependence on any loadable modules, but I'm not 
100% sure about that. Were these two functions put after grub_load_modules() 
before they might require modules loaded there?

 --S