v4.19.13 snapshot.
diff --git a/arch/um/drivers/mconsole.h b/arch/um/drivers/mconsole.h
new file mode 100644
index 0000000..44af737
--- /dev/null
+++ b/arch/um/drivers/mconsole.h
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#ifndef __MCONSOLE_H__
+#define __MCONSOLE_H__
+
+#ifdef __UM_HOST__
+#include <stdint.h>
+#define u32 uint32_t
+#endif
+
+#include <sysdep/ptrace.h>
+
+#define MCONSOLE_MAGIC (0xcafebabe)
+#define MCONSOLE_MAX_DATA (512)
+#define MCONSOLE_VERSION 2
+
+struct mconsole_request {
+	u32 magic;
+	u32 version;
+	u32 len;
+	char data[MCONSOLE_MAX_DATA];
+};
+
+struct mconsole_reply {
+	u32 err;
+	u32 more;
+	u32 len;
+	char data[MCONSOLE_MAX_DATA];
+};
+
+struct mconsole_notify {
+	u32 magic;
+	u32 version;
+	enum { MCONSOLE_SOCKET, MCONSOLE_PANIC, MCONSOLE_HANG,
+	       MCONSOLE_USER_NOTIFY } type;
+	u32 len;
+	char data[MCONSOLE_MAX_DATA];
+};
+
+struct mc_request;
+
+enum mc_context { MCONSOLE_INTR, MCONSOLE_PROC };
+
+struct mconsole_command
+{
+	char *command;
+	void (*handler)(struct mc_request *req);
+	enum mc_context context;
+};
+
+struct mc_request
+{
+	int len;
+	int as_interrupt;
+
+	int originating_fd;
+	unsigned int originlen;
+	unsigned char origin[128];			/* sockaddr_un */
+
+	struct mconsole_request request;
+	struct mconsole_command *cmd;
+	struct uml_pt_regs regs;
+};
+
+extern char mconsole_socket_name[];
+
+extern int mconsole_unlink_socket(void);
+extern int mconsole_reply_len(struct mc_request *req, const char *reply,
+			      int len, int err, int more);
+extern int mconsole_reply(struct mc_request *req, const char *str, int err,
+			  int more);
+
+extern void mconsole_version(struct mc_request *req);
+extern void mconsole_help(struct mc_request *req);
+extern void mconsole_halt(struct mc_request *req);
+extern void mconsole_reboot(struct mc_request *req);
+extern void mconsole_config(struct mc_request *req);
+extern void mconsole_remove(struct mc_request *req);
+extern void mconsole_sysrq(struct mc_request *req);
+extern void mconsole_cad(struct mc_request *req);
+extern void mconsole_stop(struct mc_request *req);
+extern void mconsole_go(struct mc_request *req);
+extern void mconsole_log(struct mc_request *req);
+extern void mconsole_proc(struct mc_request *req);
+extern void mconsole_stack(struct mc_request *req);
+
+extern int mconsole_get_request(int fd, struct mc_request *req);
+extern int mconsole_notify(char *sock_name, int type, const void *data,
+			   int len);
+extern char *mconsole_notify_socket(void);
+extern void lock_notify(void);
+extern void unlock_notify(void);
+
+#endif