efi_loader: set OsIndicationsSupported at init

UEFI variables should be installed using well-defined API.
Currently we don't support much, but the value of OsIndicationsSupported
will be updated once some features are added in the future.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

Add comments. Rename a variable.

Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index b32a7b3..87db51c 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -79,6 +79,7 @@
  */
 efi_status_t efi_init_obj_list(void)
 {
+	u64 os_indications_supported = 0; /* None */
 	efi_status_t ret = EFI_SUCCESS;
 
 	/* Initialize once only */
@@ -90,6 +91,16 @@
 	if (ret != EFI_SUCCESS)
 		goto out;
 
+	/* Indicate supported features */
+	ret = EFI_CALL(efi_set_variable(L"OsIndicationsSupported",
+					&efi_global_variable_guid,
+					EFI_VARIABLE_BOOTSERVICE_ACCESS |
+					EFI_VARIABLE_RUNTIME_ACCESS,
+					sizeof(os_indications_supported),
+					&os_indications_supported));
+	if (ret != EFI_SUCCESS)
+		goto out;
+
 	/* Initialize system table */
 	ret = efi_initialize_system_table();
 	if (ret != EFI_SUCCESS)