v4.19.13 snapshot.
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
new file mode 100644
index 0000000..98bdf69
--- /dev/null
+++ b/arch/um/kernel/kmsg_dump.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kmsg_dump.h>
+#include <linux/console.h>
+#include <shared/init.h>
+#include <shared/kern.h>
+#include <os.h>
+
+static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
+ enum kmsg_dump_reason reason)
+{
+ static char line[1024];
+
+ size_t len = 0;
+ bool con_available = false;
+
+ /* only dump kmsg when no console is available */
+ if (!console_trylock())
+ return;
+
+ if (console_drivers != NULL)
+ con_available = true;
+
+ console_unlock();
+
+ if (con_available == true)
+ return;
+
+ printf("kmsg_dump:\n");
+ while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len)) {
+ line[len] = '\0';
+ printf("%s", line);
+ }
+}
+
+static struct kmsg_dumper kmsg_dumper = {
+ .dump = kmsg_dumper_stdout
+};
+
+int __init kmsg_dumper_stdout_init(void)
+{
+ return kmsg_dump_register(&kmsg_dumper);
+}
+
+__uml_postsetup(kmsg_dumper_stdout_init);