Set the default domainname as `(none)`

kernel/src/net/uts_ns.rs

@@ -30,7 +30,8 @@ impl UtsNamespace {
                 release: padded(b"5.13.0"),
                 version: padded(b"5.13.0"),
                 machine: padded(b"x86_64"),
-                domainname: padded(b""),
+                // Reference: <https://elixir.bootlin.com/linux/v6.16/source/include/linux/uts.h#L17>.
+                domainname: padded(b"(none)"),
             };
 
             let owner = UserNamespace::get_init_singleton().clone();

test/src/syscall/gvisor/Makefile

@@ -70,6 +70,7 @@ TESTS ?= \
 	timerfd_test \
 	timers_test \
 	truncate_test \
+	uname_test \
 	uidgid_test \
 	unlink_test \
 	utimes_test \