Index: kernel/generic/include/syscall/copy.h
===================================================================
--- kernel/generic/include/syscall/copy.h	(revision 11b285d87da6e1d6a1d65134694b4f971f3cdebc)
+++ kernel/generic/include/syscall/copy.h	(revision fac0ac7be7d127e6cc5c186e3c497bea39ed2e3b)
@@ -49,7 +49,8 @@
 /*
  * This interface must be implemented by each architecture.
+ * The functions return zero on failure and nonzero on success.
  */
-extern errno_t memcpy_from_uspace(void *dst, const void *uspace_src, size_t size);
-extern errno_t memcpy_to_uspace(void *uspace_dst, const void *src, size_t size);
+extern uintptr_t memcpy_from_uspace(void *dst, const void *uspace_src, size_t size);
+extern uintptr_t memcpy_to_uspace(void *uspace_dst, const void *src, size_t size);
 
 #endif