sel4: never compile syscall-using code with -fPIC

repos/base-sel4/lib/import/import-syscall.mk

@@ -8,3 +8,17 @@ INC_DIR += $(BUILD_BASE_DIR)/include
 # Access to other sel4-specific headers such as 'autoconf.h'.
 #
 REP_INC_DIR += include/sel4
+
+#
+# Compile code that uses the system-call bindings without -fPIC. Otherwise,
+# the compiler would complain with the following error:
+#
+# error: inconsistent operand constraints in an ‘asm’
+#
+# XXX avoid mixing PIC with non-PIC code
+#
+# The lack of PIC support in the seL4 system bindings ultimately results in
+# a mix of PIC and non-PIC code within a single binary. This may become a
+# problem when using shared libraries.
+#
+CC_OPT_PIC =