v4.19.13 snapshot.
diff --git a/include/uapi/linux/msg.h b/include/uapi/linux/msg.h
new file mode 100644
index 0000000..e4a0d9a
--- /dev/null
+++ b/include/uapi/linux/msg.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_MSG_H
+#define _UAPI_LINUX_MSG_H
+
+#include <linux/ipc.h>
+
+/* ipcs ctl commands */
+#define MSG_STAT 11
+#define MSG_INFO 12
+#define MSG_STAT_ANY 13
+
+/* msgrcv options */
+#define MSG_NOERROR 010000 /* no error if message is too big */
+#define MSG_EXCEPT 020000 /* recv any msg except of specified type.*/
+#define MSG_COPY 040000 /* copy (not remove) all queue messages */
+
+/* Obsolete, used only for backwards compatibility and libc5 compiles */
+struct msqid_ds {
+ struct ipc_perm msg_perm;
+ struct msg *msg_first; /* first message on queue,unused */
+ struct msg *msg_last; /* last message in queue,unused */
+ __kernel_time_t msg_stime; /* last msgsnd time */
+ __kernel_time_t msg_rtime; /* last msgrcv time */
+ __kernel_time_t msg_ctime; /* last change time */
+ unsigned long msg_lcbytes; /* Reuse junk fields for 32 bit */
+ unsigned long msg_lqbytes; /* ditto */
+ unsigned short msg_cbytes; /* current number of bytes on queue */
+ unsigned short msg_qnum; /* number of messages in queue */
+ unsigned short msg_qbytes; /* max number of bytes on queue */
+ __kernel_ipc_pid_t msg_lspid; /* pid of last msgsnd */
+ __kernel_ipc_pid_t msg_lrpid; /* last receive pid */
+};
+
+/* Include the definition of msqid64_ds */
+#include <asm/msgbuf.h>
+
+/* message buffer for msgsnd and msgrcv calls */
+struct msgbuf {
+ __kernel_long_t mtype; /* type of message */
+ char mtext[1]; /* message text */
+};
+
+/* buffer for msgctl calls IPC_INFO, MSG_INFO */
+struct msginfo {
+ int msgpool;
+ int msgmap;
+ int msgmax;
+ int msgmnb;
+ int msgmni;
+ int msgssz;
+ int msgtql;
+ unsigned short msgseg;
+};
+
+/*
+ * MSGMNI, MSGMAX and MSGMNB are default values which can be
+ * modified by sysctl.
+ *
+ * MSGMNI is the upper limit for the number of messages queues per
+ * namespace.
+ * It has been chosen to be as large possible without facilitating
+ * scenarios where userspace causes overflows when adjusting the limits via
+ * operations of the form retrieve current limit; add X; update limit".
+ *
+ * MSGMNB is the default size of a new message queue. Non-root tasks can
+ * decrease the size with msgctl(IPC_SET), root tasks
+ * (actually: CAP_SYS_RESOURCE) can both increase and decrease the queue
+ * size. The optimal value is application dependent.
+ * 16384 is used because it was always used (since 0.99.10)
+ *
+ * MAXMAX is the maximum size of an individual message, it's a global
+ * (per-namespace) limit that applies for all message queues.
+ * It's set to 1/2 of MSGMNB, to ensure that at least two messages fit into
+ * the queue. This is also an arbitrary choice (since 2.6.0).
+ */
+
+#define MSGMNI 32000 /* <= IPCMNI */ /* max # of msg queue identifiers */
+#define MSGMAX 8192 /* <= INT_MAX */ /* max size of message (bytes) */
+#define MSGMNB 16384 /* <= INT_MAX */ /* default max size of a message queue */
+
+/* unused */
+#define MSGPOOL (MSGMNI * MSGMNB / 1024) /* size in kbytes of message pool */
+#define MSGTQL MSGMNB /* number of system message headers */
+#define MSGMAP MSGMNB /* number of entries in message map */
+#define MSGSSZ 16 /* message segment size */
+#define __MSGSEG ((MSGPOOL * 1024) / MSGSSZ) /* max no. of segments */
+#define MSGSEG (__MSGSEG <= 0xffff ? __MSGSEG : 0xffff)
+
+
+#endif /* _UAPI_LINUX_MSG_H */