efi: Adjust condition for runtime relocation

Even if CONFIG_ULIB is enabled it may not actually be in use. If not,
we still need the EFI-runtime relocation to happen. Adjust the condition
in efi_runtime_relocate() to fix this.

For static linking with ulib examples, provide weak symbol definitions
for __efi_runtime_rel_start and __efi_runtime_rel_stop. These symbols
are normally defined in linker scripts but need fallback definitions
when linking statically against libu-boot.a.

Signed-off-by: Simon Glass <simon.glass@canonical.com>

lib/efi_loader/Makefile

@@ -41,7 +41,7 @@ obj-y += efi_image_loader.o
 obj-$(CONFIG_EFI_LOG) += efi_log.o
 obj-y += efi_memory.o
 obj-y += efi_root_node.o
-obj-y += efi_runtime.o
+obj-y += efi_runtime.o efi_runtime_stubs.o
 obj-y += efi_setup.o
 obj-$(CONFIG_EFI_UNICODE_COLLATION_PROTOCOL2) += efi_unicode_collation.o
 obj-y += efi_var_common.o

lib/efi_loader/efi_runtime.c

@@ -717,8 +717,8 @@ static __efi_runtime void efi_relocate_runtime_table(ulong offset)
 /* Relocate EFI runtime to uboot_reloc_base = offset */
 void efi_runtime_relocate(ulong offset, struct efi_mem_desc *map)
 {
-	/* Skip EFI runtime relocation when building as a library */
-	if (IS_ENABLED(CONFIG_ULIB))
+	/* Skip EFI runtime relocation when running as a library */
+	if (gd_ulib())
 		return;
 
 #ifdef IS_RELA

lib/efi_loader/efi_runtime_stubs.c

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * EFI runtime symbols stubs for static linking
+ *
+ * Copyright 2025 Canonical Ltd.
+ * Written by Simon Glass <simon.glass@canonical.com>
+ */
+
+/*
+ * Provide weak symbols for EFI runtime relocation markers.
+ * These are normally defined in linker scripts, but for static linking
+ * (e.g., ulib examples) we need weak definitions that can be overridden.
+ */
+char __efi_runtime_rel_start[0] __attribute__((weak));
+char __efi_runtime_rel_stop[0] __attribute__((weak));