Error when building module with efi's "grub_efi_get_variable" function

[Mat Troi]

Hi,

This is my Makefile.core.def:
...
...
module = {
  name = mymod;
  common = net/mymod.c;
};
...
...

When I tried to build I get:
mv syminfo.lst.new syminfo.lst
cat syminfo.lst | sort | gawk -f
/build/boot_project/src/grub/grub2/grub-core/genmoddep.awk >
moddep.lst || (rm -f moddep.lst; exit 1)
grub_efi_get_variable in mymod is not defined
make[5]: *** [moddep.lst] Error 1

mymod.c has "#include <grub/efi/efi.h>" and tries to use
"grub_efi_get_variable" function.  I see that in syminfo.lst
> more syminfo.lst
...
undefined mymod grub_efi_get_variable
...

Can someone shed a light on the error and how to fix?

Thanks,
Matt